Yes, all by themselves.
Unlike the Germans, the Soviets were perfectly willing to do things like trot out unarmed "combatants", in order to deprive their opponents of ammo and supplies.
There was almost no military pressure from the west when Stalingrad and Moscow were lost.
On top of that, the Soviets had the benefit of technological assistance from the west.
I hear what you're saying my friend, but without the distraction of the west on the Luftwaffe, and a large portion of their armed forces having to protect the Western front, I can't see how Russia would not have been defeated if The Germans only had them alone to deal with. I disagree, but you already know that I respect the hell out of your opinion. ~BH
But the Germans also had to fight the nasty weather of the east.
It's difficult-cum-impossible to move a land force, when the ground under you is three feet of mud or under five feet of snow.
There are, like, about four months that you can fight an effective land war against Russia....After that, you're pretty much screwed.