I haven't heard anything about Aleksander signing with UFC. For some reason, I doubt it.
By the way, why do you think UFC pays more than Pride FC? Maybe you know something I don't, but it seems unlikely. Yes, UFC is more popular here in the US, but Pride is a huge event over in Japan. It makes sense that Pride FC would be able to pay their fighters more, being they hold their events in 100,000 seat arenas. Could UFC fill a venue like that?