Sure, but it's not all to keep. He is a business (or his label is). He has personnel expenses, production expenses, studio expenses, expenses, etc.. If he keeps 1/4 of that $350k, he's doing well. Multiply by a small number, maybe 3 or 4, to account for his other income streams.

He's a pretty well-known artist, one of the top X. He ought to be making a good living, and maybe he is - but I doubt he's getting rich.