My personal calculus has revolved around the hundreds of thousands of Ukrainians that have been kidnapped and transported into Russia. It hinges on whether the Ukrainians can acquire something of value, and offer it to the Russians in exchange for getting their people back.
For me, those lives are paramount. I'd be willing to consider a substantial trade of territory and other things, to get them back. I would think it a great tragedy if the Ukranians were able to drive the Russians off their Crimean land bridge, but never saw those kidnapped Ukrainians again. I would consider trading the land bridge back to the Russians, in exchange for those lives being returned to Ukraine. I would consider giving up claims to the "separatist" regions, in exchange for those lives.
I'm not saying a Russian total or partial victory on those terms is preferable to continued war. I'm saying that's the central question, for me, about whether Ukraine should keep fighting or seek some sort of compromise that brings peace by giving the Russians something they want.