Before 1900? And without additional territory?
Start counting moose as people?
Canada is empty today, with a population density along the lines of the Sahara...
What's the driver? As it was, Canada even after Confederation had a difficult time attracting emigrants, certainly from Europe, and I don't see much of a willingness to open the doors to Asian emigrants, even today.
Best,
No, there arent nearly enough moose.

Seriously this is ASB. Sorry, but... The Prairies can't grow enough food to support a high population until 1) the introduction of the steel plow and a functional reaper, 2) short growing season wheat is bred.
Moreover, you need a railway to get that food to the population centers and to get goods into the prairies.
If a functional StLawrence Seaway had been built a century earlier, you might have been able to get away with rail just from the Lakehead to *Winnipeg (building rail from Winnipeg to the Rockies is trivial, whats really, really hard is the Canadian Shield portion - and through the mountains, but thats a shorter length)
Of course, relying on a transport mthod that leaves the western half of the country out of communication with the east for a third of the year is just asking for trouble.
OK, so. An earlier seaway, a lake/rail.connexion west in the 1840s, not reaching *Vancouver until sometime in the 1850s. A nativist US, so the people coming to Canada stay instead of heading south....
Could you get Canada to 50 million or more by today? Probably. But the US is amazingly rich in resources and land, and isnt nearly as linear. It's beyond comprehension that Canada could be more powerful than the US.
Could Canada be a Great Power, like Brtain or Germany? Yes. Tough, yes, very tough, but doable.
Can it be a Superpower? That would surely mean both Superpowers in the world are in North America, which at best seems unlikely. What happened to Europe?
No. Canada being a Superpower is, at best, close to ASB, and any way it could come close would involve Vlad Tepes levels of devastation in Europe and possibly Asia. Without significantly affecting Canada...