The reserves are there, but we are already seeing the effects of the sanctions. As I mentioned, the ruble is in free fall. The stock market didn't open because of where it would be and how hard the crash would be.
I think he cannot last very long. He has diversified his economy somewhat and tried to make it less reliable on the dollar, probably thinking that the U.S. would be pushing him the hardest, but he diversified into euros, and now the EU is pushing him very hard.
I don't think he can last a very long time.