He does. He's the top selling artist out there right now, even more than Eminem, and everything he touches is a hit record. Styles P said his album got delayed because 50 Cent told Jimmy Iovine he didn't want it to be released yet. Maybe the only guy above him at Interscope is Dr. Dre
I don't think MOP, Mobb Deep and Mase are big signings, but all they have to do is throw 50 Cent on a single and they'll sell, it worked for Lloyd Banks, Young Buck and Tony Yayo.
And anyway, I don't think there's going to be a 50 Cent-Jay Z feud. If there is it's going to be pointless because even though Jay would kill him lyrically, it wouldn't do anything to 50's popularity.