No, they don’t. Valve does not ever dictate prices to people listed on the platform.
And while it is laudable to want a larger cut in the dev’s hands there are a lot of things that Steam does for developers that Epic simple doesn’t do.
Steam will cut Steam keys for free for the devs to do with as they wish. This is how sites like Humble Bundle and GoG are able to offer Steam keys. There is no per-key activation. Steam also eats the cost of distribution (bandwidth, server, etc). So when you purchase a game from another storefront which offers Steam keys that is costing Steam money.
Valve also puts a lot into R&D. Now, you personally, might not get use out out of those features, but a lot of people do. Especially devs. Long story short, Valve is looking at the gaming industry as a whole and trying to keep it open and free as possible. This is why they tried to make the Steam box. This is why they are hopping into VR with the Index controllers and their upcoming VR rig. All of their hardware offerings have had their driver side support be open source. Steam Boxes were based on a modified Ubuntu, the VR driver side is open sourced. In fact they have gone heavily into Linux gaming with the introduction of Proton; WINE baked into Steam to allow Windows games to run on Linux.
So, from the dev perspective here’s what you get from Epic. A buttload of cash up front, a better cut (if you’re an indie or AA dev), waiving of the Unreal Engine 4 cut (if you’re using that engine). All you give up for that is practically all the decent storefront features, security, ability to sell on other storefronts (though Epic is somewhat changing that), and the goodwill of a good portion of your fan base.
From the customer perspective here’s the difference between the two storefronts. Valve, whether people agree with it or not, have always tried to put the customer first. All of their moves have been in an attempt to try to get more power into the hands of the consumer. That is why they go so heavily into open source technologies. Hell, I’d be surprised if they don’t start working with Godot to help get a cross-platform, open source, game engine to a state where it is a competitor for everyone.
With Epic not only are they bringing one of the most reviled practices from the Consoles to PC Gaming (exclusivity), they are doing it in a very scummy way (see Metro Exodus), all the while offering a far inferior customer experience (storefront), no benefits in costs to the consumer (All former Steam announced titles have been priced the same on EGS), a worse experience to international customers (no regional pricing, passing the cost of the payment processor to the customer instead of eating it like Steam does), and a track record of doing very little for the overall for the gaming community, will shut down a lot of Indie development (Epic plans to not allow many indie titles on their store), disallow customer feedback (game reviews can be disabled by the publisher).
Do I, as a consumer, want a cut of my money to go to a company that has tried to expand my power as a consumer and tried to encourage openness and freedom in the gaming industry. Or the company that is actively hostile to me as a consumer and trying to kill the former?
Personally, I’m on option one there. I’d love to play Borderlands 3. The instant they went to EGS is the moment they lost me as a customer. The same goes for Division 2, Outer Worlds & Phoenix Point. By going with EGS, and especially by not lowering prices in light of the lower storefront cut, they have proven that they are actively hostile to me as a customer.