In otherwords he can still ramp up, then the west simply continues squeezing Putin and Russia for a year, or 3... then he can either go take back Crimea/Donbask regions, or perhaps wage a coup inside Russia -- get the oligarchs to agree to a Democratic Merging of Ukraine, Belarus, Russia with Zelenskyy as President for the first two terms, and with a path towards NATO and EU membership - which would be a HUGE finger to China and a big win for Democracy.
This essentially gives both sides a ceasefire but western pressure on Russia slowly strangles them to the point of collapse, and Zelenskyy can then basically take over, as he's basically a Hero for many in Ukraine and Russia and even Europe and USA. I mean a comedian turned President against Putin and he's holding his own pretty well - it's David vs Goliath.
IMHO that's the best option. As for this war, whether Zelenskyy does this or not. Putin has lost Russia. It's a matter of time before he's deposed after this blunder. Russia will never win in Ukraine.
Option B: Hold out a month, and basically Russia might be at the point they'd give him Crimea, Belarus, and Donbas if the west just eases up a tiny fraction on sanctions.