The Epic First Run programme allows developers of any size to claim 100% of revenue if they agree to make their game exclusive on the Epic Games Store for six months.
After the six months are up, the game will revert to the standard Epic Games Store revenue split of 88% for the developer and 12% for Epic Games.
Valve do take a larger cut, but that money is going into some incredible services both for consumers and developers with Steamworks. Much larger audience too, which makes up for the larger cut anyway.
Epic just want a slice of the revenue while putting in minimal effort, so they just buy exclusives and free game promos, so as far as I am concerned they can fuck off.