The simple fact is that Russia can't force a victory, and neither can Ukraine. So the issue becomes who can hold out the longest, and with the support it's getting, that's probably Ukraine.
The only way to stop Ukraine from joining NATO, by the way, is to keep the war going. As soon as there's a peace deal, Ukraine will apply to join NATO and will probably be accepted this time. If Russia wants to prevent that, it has to offer security guarantees to Ukraine that are a lot harder than the ones they broke last time, and that will include returning all occupied land. I think that's very unlikely to happen.
Russia will probably keep Crimea, because that's impossible for Ukraine to take back. Even so, they might be stuck with sanctions.
I can guarantee it because NATO and the Western countries are only willing to sacrifice money. Once it escalates beyond that, they will pressure Ukraine to compromise with Russia or simply walk away as they have so many times before.
And I'm not sure why you think Ukraine can outlast Russia? Russia has 10x the GDP and 3x the population. They're also holding oil and gas over Western Europes heads.
Take a look at the exchange rate for the ruble. It's higher than before the war. Russia is forcing people to buy their gas with rubbles. They have way more leverage than you think they do.
Again, you’re making the same mistake nations make when they get into wars.
I guarantee when the shooting stops - 1) Ukraine will have lost strategic territory, 2) Ukraine will not be a part of NATO and 3) NATO will disengage.
That’s a full on win for Russia. That’s exactly what they stated they wanted back in 2015.