Will Ukraine do any sort of fighting back? I ask because it seems to me that the Western politicans are constrained by public opinion. They will not issue major sanctions if they don't have to, they'd rather keep the markets afloat. In my view only real visceral footage of the horror of war could compel the Western publics to actually get mad to the point where the politicians impose serious sanctions on Russian gas exports and banking.
Define "fighting back". If you mean they will attempt to defend their land and cities, then yes. If you mean strike back at Russia then no chance. Ukraine simply doesn't have the tools necessary to mount any sort of counter-attack and even if they did the Russians effectively have them surrounded right now. So it would have to be ICBMs or similar long range weapons which they no longer possess.
Unfortunately this is what happens when countries are pressured to de-nuclearize, promises of Western protection and then fall to bullies.
I don't expect them to occupy the rest of Ukraine. They will probably settle for destroying large parts of the Ukrainian military.