Romney may have closed slightly without it, but there is no way the money would have kept rolling in nor would he have been "really in it" without that first big debate win. The problem for Romney was that he needed a second debate win, preferably at the townhall debate to finish the job with regards to the comeback and instead that was a disaster.
Romney's performance in the second debate was not much worse than in the first. The difference was all on Obama's side.
Whether you win or not, depends upon your performance
relative to the other guy's and the format of the eventYou can't replicate the first debate strategy and tactics in a townhall style event and the fact that both tried to do that resulted in both screwing over the format and riding rough shod over the questioner. Had one refrained from doing that, I think they would have gained significantly with independents and undecided voters. Romney needed a seperate and distinct "townhall debate strategy" aimed at connecting with the problems average Americans are facing and connecting his solutions to those problems as part of his vision for the future. Instead he was playing the tit for tat, each man correct the other game that Obama wanted to play, which ended up draining Romney and caused him to lose his focus by the time of the Libya question, when a perfect opporunity for him ended up getting turned into Obama's best moment.