No one disputes that. Russia would have most certainly lost if Germany wasn't fighting on two fronts. The Soviet people defeated Hitler, not Stalin just as it will be the Ukrainian people who will defeat Putin. It should be obvious why we don't have a statue of Stalin. A: He was not a Canadian. B: He was a monster who killed more of his people than the Germans.
"Not being Canadian" is a weird criteria given we have statues of various non Canadians throughout the country, including Churchill. As for the being a monster part, isn't your argument that we shouldn't balk at statues of people who had complicated or problematic histories?