Well, first of all, tortoises don't belong in cages. If you can't set him up outside where he can roam and graze, then indoors he needs something big, like a 5 shelf book case laying on its back with the shelves removed.
Russian tortoises hibernate, so there's really no reason to keep on in the house during the winter. Set him up outside and box him up in the winter for hibernation.
A good Russian tortoise web site is: russiantortoise.org