Sure they can.
Rockets shooters normally play much better at home.
Rockets came back form 19 down in the 4th and Harden didn't even play. If Smith, Brewer and Terry shoot better, they won't need Harden to score 40. Harden hasn't been going off for most of the playoffs and they've advanced.
BTW, Steph has averaged over 30 points per game and they have won by 4 points and 1. I'm not so sure GS can win if he doesn't have a big game.
You right but I trust Thompson, Green and Barnes to carry some of the scoring slack if Steph struggles than I do Josh Smith, Jason Terry and Corey Brewer to carry the slack when Harden struggles.