I think the next fighter on the god side will probably be either be Anubis or Apollo. Their saving Odin, Buddha, and Loki for later on in order to build up hype. They wouldn't likely use Bishamonten the fight after he's introduced at least until the Buddha situation has been resolved or been delved into further. They wouldn't follow up a fight involving a japanese fighter with a japanese god so Susanoo is a no go that leaves us and I would be astounded if Kintoki doesn't end up being the last round of the tournament and his opponent is a given. So that leaves us with the two expendables Anubis from a pantheon that hasn't really had a presence in the plot outside of some audience shots or the last of the Olympians Apollo trying to see if he can salvage his pantheon from maintaining meme status.
True the creators could definitely prove me wrong this weekend/Monday but considering the two somewhat iron clad givens I think this series will have I think that my 6th round prediction will be a pretty safe bet either Apollo vs Simo or Anubis vs Qin/Rasputin... though I honestly think for those two human reps also have fairly solid arguments for why they would face off against Buddha as well.