Russian spies in the US government is a typical paranoia created from the end of the cold war when russia got back up from it's feet, after the collapse of the USSR by some journalists and theorists who are not even security expertS.
The same people who were saying that Trump is a russian satellite are saying that Gabbard is another. For some US politicians who are poor chess players, they end up getting compromised with sextapes by foreigners like the russian. Sextapes do not allow a total control of a politician, simply a defense measure if he decided to go against your interests in an aggressive way. It's more a shield than a sword on the scale.
To believe some media, who want to create false drama, you don't have a dozen of russian spies in each gov institutions, because simply to get there, you need a clearance and to be part of the US intelligence community.
It's simply the price of the commodification of information and journalism, you will say anything that will sell and make drama for money, even if it is false. Trump is not a russian spy, as gabbard is neither a russian asset.