There's no smoking gun evidence that is accessible, and there likely never will be. There is some circumstantial evidence that seems compelling. We know that scientists in Wuhan were working on this exact type of virus and were also working to make it transmissible in humans. We also know that there were issues reported in safety protocols at this/these labs. Finally, we know that the virus outbreak happened in the same city (and possibly within a very short distance) of these labs.
Presumably (I have no data on this and would love some from anyone who knows more), there are not many labs doing this sort of research, so the fact that the virus appeared in the immediate vicinity of one of the few labs where they were doing this research seems like a heck of a coincidence. It's not a smoking gun, but I'm a little concerned to see people in the scientific community writing it off as a near-impossibility. What's wrong with saying, "We think that this is unlikely given xyz, but the circumstantial evidence is concerning and we should reevaluate all research of this type."