Starting with a question "What is it that the companies look for when they decide to sponsor an event?" I am quite sure the answers would be "Age of attendees, number of people attending (so they can figure out cost of reach (sponsorship amount / number of attendees), type of the event, general profession of attendees etc.).
Using that information you can build individual landing pages that speak to that particular type of the company.

For example, if you are trying to sell to a law firm, landing page that shows demographics from NYC LegalTech will go a long way.

Option number two (this worked for us, so I am not sure how it would translate) is finding a list of attendees from the particular conference and then creating demand by sending "These people are looking for solutions like yours" emails to decision makers at the companies you are targeting.

Hope this helps a bit. If we view this from a bigger picture perspective, you need to do what advertising industry has been doing for a while, and that is, you need to break down each event into key metrics and demographics and then use those to sell to the prospective sponsors.

What you need is a clear inbound marketing strategy, which includes content marketing (blogging, ebooks, infographics, videos, images, audio, etc.), social media marketing, email marketing and PPC. Heavy emphasis on content marketing.

FYI, you should look into this:
https://sponsorist.com/
http://www.sponsorhub.com/

In addition to Viktor's questions you need to answer:
1) Who is your audience?
2) What are their pain points?
3) Where are they online?
4) Who are the influencers in this space?

The process by which you bring new clients or customers to your business is customer acquisition. The goal, for any company, is to create sustainable and systematic customer acquisition strategies that keep up with industry trends. Lead acquisition is the middle section. Customer acquisition, however, is the entire end-to-end process that involves all these stages. It is only a matter of discovering who they are and focusing your customer acquisition efforts, primarily, on them. If you do not have a target customer in mind, it is likely you are limiting yourself from marketing your brand effectively. It forms the foundation without which any of your other customer acquisition strategies would not work.
Building upon what we discussed above, it is not enough to know who your ideal customers are. It’s equally important to know the right channel to use to acquire said potential customers. Now, there are several different frameworks that can help you identify the best channel to use for your customer acquisition strategies. Video marketing is on the rise. That is because 97% of marketers have found video content useful to increase customer understanding of their offerings. Another 76% have found it helpful to increase web traffic and sales. Explainer videos and customer testimonials are another good way to go about this. Companies like Okta have benefited a lot from customer acquisition strategies like video marketing. Often, customers need more than just words or promises to convince them to pay for your products and services. Some of the more persistent consumers will not even be swayed by influencer or word-of-mouth marketing. To win over these consumers as loyal customers, you should consider doing giveaways. The easiest way to implement such customer acquisition strategies is to run giveaway campaigns on social media. Content marketing is easily one of the most effective and evergreen customer acquisition strategies there are. Getting consumers to trust your brand is half the battle and content marketing helps you win that battle. From a lead generation perspective, content marketing is thrice as effective and 62% less expensive than typical outbound marketing. Starting a blog for your business, sharing content on social media, and publishing white papers are all great ways to establish yourself as a trustworthy expert in your industry. Consumers are more and more informed these days. Creating valuable, informative, insightful, and engaging content will, ultimately, help drive your customer acquisition.

Thereby making your content more visible and discoverable by your target audience. Improving search rankings and your brand’s visibility has a lot to do with the first stage of the customer acquisition funnel. Another effective SEO tactic you can use to gain more customers is to optimize your site for mobile devices. Providing prospects with an excellent mobile experience can prove to the trick in converting customers. Starting from keyword research to on-page SEO and competitor research, this tool has got it all. Referral programs often serve as the basis of many customer acquisition strategies, especially when you are a fledgling company. And you can also offer these new customers similar discounts to give them an extra nudge to leverage your services. Among other customer acquisition strategies, optimizing your landing pages is one of the most effective ones. Landing pages help direct consumers to your product or service. An effective landing page does not just offer up valuable information but also includes a compelling call-to-action that facilitates conversions. It goes back to knowing what your customers expect from you. This is an iterative process, and you should keep experimenting to figure out what is helping win more customers. Ones in that have you in their consideration pool would be more interested in emails with product information. They are always sending out customized emails to their audience.
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath