Estimates place it higher than that [0]: "Broken down further, "Fortnite" is said to have made $1.6 million each day on Apple's devices; if Apple is pulling in its standard cut of 30%, Apple made somewhere in the realm of $136.5 million on "Fortnite" in 2018.".

[0]: https://www.businessinsider.com/how-much-does-fortnite-make-...

Still, they are unlikely to be the real issue for Epic. I'm fully expecting some anti-consumer behaviour from them if they get away with their own payment system, like difficult to cancel payments, gambling or similar.

Apple is in a constant state of being involved in lawsuits, though of course not all are of the same significance. Their legal team has a lot on their plate.

You don't know that unless you know what the legal costs are, their odds of winning the suit, the lost $$ and opportunity cost due to no sales on iOS, the revenue loss from their 20% discount on V-Bucks, etc.