As long as the testimony is not from one of the involved parties, yes, eyewitness is evidence. The lowest tier of evidence, mind you, since it has been proven quite unreliable, even with cross-examinstion and the likes (sorry if it’s not the word, not a native English speaker).

But yeah, if it’s not the accusing party, or any party with interests in the matter, and it is proven there is no coercion or personal interest, it should count as evidence.