i suppose that if he had pulled back after Smolensk he could have salvaged most of his men, though his army still would have suffered quite a toll from the summer heat and diseases in addition to the bloody battles, and he was losing horses extremely quickly. It also would have made sense to pull back at that time because he'd already gone a lot further into Russia than he'd planed (having not anticipated the Russians to give ground so readily).Like, maybe, not invading Russia? Or at the very least not trying to take Moscow in one year?
after that battle he only narrowly missed out on catching the commanding General Barclay because Davout didn't feel like pursuing right after crossing the Dnipro. in the short term catching him would be a win, probably enough for him to finally force Russia to the negotiating table. but the Russians were at the point were they were tired of getting pushed around so they wouldn't be honest negotiators. Napoleon was also just absolutely terrible at making peace treaties by this point, probably incenses Russia further by expanding the Duchy of Warsaw to punish them for resisting, before pulling back. then next spring he'll be facing down a surprise Russian offensive.
thats how i see that playing out at least