hmm, interesting. ok, my first response was that he's got the 10 and check-raised. however, looking at the problem again, it's obvious that the 500k continuation bet meant he had nothing. therefore, jimmy would be able to guess relatively accurately that gus didn't hit the flop. gus does have outs, however, and wouldn't be in that bad a shape if jimmy had a J.

assuming that the chipcount is now around 10 mil vs 5 mil. If he lets this go, it will be around 9 vs 6, still a commanding lead.

I think this would be a good fold to preserve the lead, but calling wouldn't be bad either. I'd say it's about a 50% chance he's on the pure bluff, 30% he's got Jx, and 15% he's got A10 or another 10, and 5% he's got j10 and already made the full house.

You have to fold. Jimmy has either made a very good draw or mayabe more likely a set or FH. There is simply no reason to bluff at the pot at this point. If Gus folds, he's still relatively in the same position as before. If Gus calls, Jimmy's out. To me, this isn't that difficult. I got nothing but some questionable draws at this point and I can keep my 2-1 chip lead by folding. If Jimmy bluffed us, then good for him, but that is a profoundly bad spot to bluff.