He should be upset he had more votes than Hillary but didn't win...
According to THIS
compilation Clinton received about 3.8 million more votes than Sanders. And Sanders did well in states with open primaries which suggests that without the help of independents he wouldn't have done as well against HRC.
BTW, I haven''t heard many people — any
, actually — claim that "Russian influence" cost Clinton the election, only that Russia successfully attempted to disrupt the normal campaign process by sowing doubt and confusion, and hindering electronic communication. This is hardly the only instance of Russian meddling in elections; at the moment they are pretty busy in Europe.