Such a stupid way to look at it. Obviously if you can walk away from the battle and live to tell the tale then you are the winner. If you cant then obviously you didnt win as your opponent killed you as well.
Which is irrelevant, once your opponent is dead, the battle is over, whatever happens after that is irrelevant, same with a post-battle death, if you die
after the battle due to whatever reason, it's irrelevant, the battle is over. That's the same as you fighting someone, and you end up killing that someone, but that someone wounded you and you couldn't get medical assistance in time and you died. That doesn't equal a draw, you killed your opponent
during the battle, while your opponent wounded you to the point that would cause your death
after the battle, we're discussing the battle itself and its duration here, not what happens before or after that.