No, it was a draw. Neither of them beat the other, and by the end both were disarmed and fairly worn out. This doesn't really match up to Yoda declaring he's failed and must go into exile. There's nothing to stop him trying again tomorrow.
No, it was a loss, yoda only had one shot to try and sneak in to kill palpatine. Up until he made his move, the emperor didnt know he was still alive, or that he intended to come back and kill the sith lord. Now he is on his guard and everyone in coruscant is looking for a little green man who tried to assassinate the emperor. Strictly speaking from a combat standpoint it was a draw, but as far as end results go, it was a loss by yoda, because he failed to kill the sith lord, and now he will have an entire empire hunting him down. Palpatine is the winner because he is still the emperor, still in command, and still alive. It isnt a total victory, since yoda escaped, but it was still far more heavily slanted in his favor than yodas.