That statement/accusation has been in the news for years, no one really knows what he controls. In a way it doesn't matter because if he doesn't control a Russian company today, he could have it by tomorrow.
My feeling is he is now playing for the history books, he wants to be "Putin The Great", who rebuilt the Russian Empire after the collapse of the Soviet Union.
Here is a horrifying thought, what will happen after Putin dies ?
Empires like this often don't outlive the man who created them. Ukraine will want Crimea back, Georgia will want its stolen territory back, the 'stans' will want more independence, etc...