I've heard this a lot before but I personally don't see any real connections to Yu Yu Hakusho in anyway, there might be some but I don't see any. Most animes are influenced by at least one form of another show, it's not exactly a rip off until it goes too far.
But honestly Yu Yu was influenced by Drangonball and Sailor Moon(no really it was), so do you also consider that a rip off? What about Naruto, it seems like DBZ with ninjas to me. Inuyasha or DBZ for girls? Bobo-bo the influence is uncanny.
Btw there's a Sticky thread for all you Bleach needs if you want to know more about it or just watch it.
http://forums.khinsider.com/showthread.php?t=10517