Doubtful, their manpower is simply too big. But Russian population is aging badly like us so they won't be able to keep their military up in the near future. The plan over here anyways is to make it as expensive and pointless as possible for them to invade, making sure it would become a long guerilla war in the forests.
Sure they can bomb and capture the cities and murder civilians as they always do, but the forests are difficult and are full of large rocks brought here by the ice age, making them inaccessible for vehicles. Unlike Estonia for example that is very flat and will be easily overrun