“Yet they keep advancing and taking ground.”
As the Germans did until 1943; then...ooops!
Bad analogy; Ukraine ain't the Soviet Union with loads of manpower and space to trade, and the West's resolve is more akin to 1939 and not 1943. About the only thing turning out to be even remotely similar is the modern "leaders" abilities to screw things up which will most likely lead us into a world wide conflict no one wants to be in.