I think people are interpreting "asset" in different ways.
An "asset" can just something that is useful. If you interpret it that way, it's not difficult to make the argument that Tulsi Gabbard may be an asset to Putin. While not a serious contender, Tulsi is a bit of an attack dog against her own party at times, which could help lead to a Trump re-election. She could also become a 3rd party candidate that steals Democrat votes and helps to get Trump elected.
I think other world leaders (Putin, Un, etc) see Trump as doltish and easily manipulated, so it would make sense that they want him in office. In that way, they could very well be pumping out propaganda in favor of Tulsi. That's not very far-fetched at all. We actually already know for a fact that they are doing things like that (not for Tulsi, just in general).
But an "asset" can also be property. In which case, it's sort of a silly conspiracy theory to actually believe Gabbard is in cahoots with Russia. That is not something I believe at all, or even take seriously.
Maybe the better question would be, "Do you believe Putin appreciates Tulsi's presence in American politics because of the likelihood that she provides some small help in getting Trump re-elected?"
My answer would be that I have no idea. But it's not really a difficult scenario to envision.