Well yeah he gets a kick back and probably much more over the lifetime of the deal
The way they trap them as far as I've seen is usually by setting an arbitrary condition to complete the contract and then moving that goalpost
So for example, they'll give you a 5 album deal, give you an advance for each album (which is the loan/budget for the albums), and then from there take a percentage out of everything you do musically from that point forward. Then they can decide that certain things don't or do meet the criteria to be called an album, decide not to clear certain songs, etc. All type of fukkery to keep you under contract
Corporate bullying, really
Edit: this isn't to say gotti is robbing all his artists cus he very well could be doing good business, I'm just saying that this is usually how those things go