That is… Likely not correct. Finland came very, very close to losing the Winter War; Russia pulled back because they didn’t realize that the Finns were on their last legs. Yes, Russia right now couldn’t walk through Finland, but at the strength they had prior to invading Ukraine? It’s much, much more probable. The military of Finland is tiny compared to Russia; 292,000 (about 25k active, the rest reserve) compared to 3,159,000 (1.1M active); looking solely at active military, that’s 44:1, Russian advantage.
The big thing that would stop Russia now is NATO, since all countries are pledged to help any other member country if (when) Russia invade. The US is a significant part of NATO, both in terms of raw manpower, and in terms of money spent on the military. Without NATO, Finland probably loses, as long as Russia presses their attack. With NATO, but a NATO without the US, Finland wins, but it takes years. With both NATO and the US, Finland takes Moscow in 2 months.