First off, I don't think they will game 6. In fact, I feel even more confident in saying that than saying all season that the Spurs would beat the Thunder. And despite how bleak it looks now and what you may have thought of that opinion, if you saw any of my comments on this match-up, you know I was indisputably supremely confident; so to say I'm more confident now is saying something. But predictions aside, it is still technically a possibility and a very real one. It's not as if they've got to come back from 0-3.
So let's go out on a limb for a second and say they pull it off and force game 7. What chance would you give them in it? I'd give them anywhere from 30-40%. Asking the big three to play the type of minutes and exert the type of energy is would require to win three in a row, when this series has been going every other day for a couple of weeks, is probably asking too much. They'd hang tough, but probably fade down the stretch. In other words, I don't think this is a matter of, "if they can just find a way to pull out game 6, they'll win game 7".