Assuming that the claim Trump's attorneys are making (that Trump actually won more than 70 million votes and got over 400 electoral votes based on the data from the server they got in germany) are true, that would be an absolutely incredible scandal.
They definitely need an overwhelming amount of evidence to prove it though (and for the supreme court to take up the case for constitutional reasons). Supposedly they have that evidence because Trump definitely hasn't given up yet, despite a few courts denying to hear the case.
If the supreme court takes up the case to investigate, then it's highly likely that they do actually have that evidence.
Just have to wait and see what happens.