It's been proven time and time again that Trump is untouchable. He joked about being able to shoot somebody and not lose voters, and it's too true. People that love Trump love him because of the people he hurts, not the people he helps. If he shot someone, his supporters would be like "haha he murdered someone! That makes you so angry, doesn't it? MAGA!"
So, no, I don't think Russia could blackmail Trump. Any dirt Russia has on Trump could be released and it wouldn't decrease Trump's support. For fuck's sake, we already know he was a regular visitor to Epstein's Kiddie-Diddle Island.
D Russia can blackmail Trump
E Russia pay Trump to act in favour of of Russia even at the cost of US interest.