Investors look at a potential investment as risk vs reward. How much risk is this investor taking on by giving the company money now for your team to show product market fit? A key to this question is for you to understand the steps necessary to get your company to the next stage. Right now, you're in the easiest stage -- building product. The next step (which is way harder) is to show that your product has demand and your company can attract customers.
Each company is different, but considering you've signed deals with 7 content providers (I'm unsure of how many there are in the market), it looks like these content providers are your main customers. You should have a clear understanding of their KPI's to ensure that your contracts will get extended. I assume that this will tie to impressions, click-through, engagement, etc, but that's for you & your customer to establish, and for you to communicate effectively to your investors. Having a clear understanding of what these metrics are, and why they are important, will be very valuable for your investor discussions.
In determining an equity valuation, you should look at other companies in your stage & industry and see if you can peg a valuation to those deals as comparables. You can also propose issuing convertible notes at a certain valuation cap -- this way, you won't need to set a valuation now (it will be set when you're ready to raise your series A) and your angel/seed investors will be able to have an immediate gain if your valuation skyrockets.
DISCLAIMER: our company raised a convertible debt round at sub $2MM.