I see an Akira screenshot, I upvote.
Overspark
This isn't public data unfortunately, devs with a game on both platforms are the only ones who can tell us where they earn more. However, I did once read an article that claimed the effective cut from Steam is about half what it says on the tin IF the devs (or their publisher) put in enough effort themselves. Because that's who decides this, Steam doesn't have and doesn't want any control over this.
Except that's also a lie. Steam does keep a higher percentage of the sales price for itself than Epic does, but it also allows people to activate game keys without taking any money. Steam only makes money from games sold on Steam itself. So developers can sell games through other stores and even through their own website, and keep up to 100% of the sales price. Effectively, this means that Steam takes roughly the same amount of money that Epic does, or in some cases even less probably.
As someone whose eyes are currently feeling a bit dry, this is a soothing fact, not disturbing at all.