But Revan should be a man behind the mask the first time he came around, shouldn't he? He seems to wear that mask all the time, even when he discovered the SM in Dantooine. That way, Jolee should never have seen his face and recognized him.
You could argue even if Jolee didn't see Revan's face he knew the PC was Revan because the Star Map in Kashyyyk opened for him. But well, the Star Map could open not only for Revan, right? So again this argument doesn't stand.
So I reckon it's through the Force.
And indeed Jolee could have seen Revan in the jedi order before he left. Plus Revan at that time during training could not possibly have adopted the mask-wearing practice. So this could also be why Jolee knew it.