Airforce, you left out the headline in the page you linked to: "War could be over by May, says Ukrainian presidential adviser" You can't believe the Ukrainians. That is just wishful thinking....
When the war started, I didn't think the Ukrainians could last 10 days. We're twice that now, the Russians have taken heavy losses, and they still don't have Kiev, or Mariupol, or Lviv, or most other major cities. The Russian plan seems to be to turn these cities to rubble - but rubbleized cities make them harder to occupy (see Stalingrad and Monte Cassino, among others). So yes, it certainly is not out of the realm of possibility the Ukrainians could hold out until May.
