I think the truth probably sits somewhere in the middle. One the one hand, he clearly didn't realise that Ukraine wouldn't just roll over and surrender, nor that most Ukrainians would be hostile to incoming Russian troops, nor that his forces would perform so badly due to poor equipment, poor leadership, low morale (etc etc). All that speaks to him having previously been living in a shell of some kind.
One the other hand, he was probably aware of the shattering of those illusions within the first week of the invasion. And now he's stuck with it: unable to retreat his forces back into Russia/Crimea, because that would probably be the end of him, but also seeing his forces unable to make significant breakthroughs.