#Russiagate has a couple of 'trails'. The first being the hacking of the election. The second being whether Russian interests are getting preferential treatment in the US in exchange for money or deals favorable to Trump (and others') businesses, i.e. a quid pro quo for contracts or favorable legislation or de-regulations. And if so, can specific illegality actually be proven.
If the former hasn't happened, I'm sure the latter has. It's just whether or not they've been illegal and blatant or simply 'legal but unethical'. Trump is a champion at legal but unethical as are many of his Goldman Sachs cronies. And I'm sure that, no matter what has happened, they are being very sure that Trump has plausible deniability. He's the key to continuing this shady shit.