Pain is the clear winner here.
Pain can absorb killer bee's beast balls and chakra arms with preta path.
And if killer bee uses his taijutsu. Pain can use human path or naraka path to either take killer bee's soul or basically kill him without him being able to stop it.
Pain can also use chibaku tensei which I see no counter to in this situation. There also is animal path that gives pain even more power.
You also have to consider that it's basically a one vs six situation here because of all the paths. The paths can also see out of the eyes of each other which gives them a big advantage.
In my opinion, I see no way that killer bee can win. But I would like to see some counter-arguments.
-Momoshiki is the only Rinnegan user that’s been shown to be able to absorb TBB, and his Absorption technique is different from the Preta Path’s; So that’s a no, the size is the problem. TBB fired at various directions forces all of the Paths to retreat behind Preta.
-Bee is very skilled in taijutsu and kinjutsu, when he‘s holding all of his swords, he’s unmatched and with Samehada it’s a different story. Those Paths of Pain will have to touch him in order to take his soul.
-base form Bee withstood a Chibaku tensei from Edo Nagato, so that won’t do much to him.
-It’s 2 v. 6 since Bee’s a Perfect Jin. Bee has a healing factor, can make Ink clones, destroy the environment with explosions and/or using the method seen at the beginning of chapter 566. He’s also an escape artist, and for that reason I believe he was nerfed to let Naruto take the helm.
Pain will still win, but it won’t be neg diff.