If the French Army was destroyed with him, that might just bring the whole series of wars to an end. If the Austrians and Russians can push on into France, they might just restore the absolutist regime.
If you mean Napoleon is killed by a sniper or whatever, the French Army might faulter and possibly wouldn't win the battle. What would happen next depends on who takes over after Napoleon. If it's somebody who knows how to quit while he's ahead, Republican/Imperial France might retain a great deal of land added to it after 1792.