Really? Where do you get those numbers? Two thirds of Russian immigrants claiming to be Jewish have no Jewish relatives? I'd assumed there were a few, but not so many.
In NY, it seems most Russian immigrants are Jews. I've passed many Jewish centers/synagogues with Russian lettering, but have yet to pass a Russian Orthodox church. (Not that I've been everywhere in NY, mainly just parts of Queens and Manhattan).
Jerusalem Post: New demographic time bomb