Given that he was outnumbered literally 6.66 to 1, I highly doubt he wins the battle, even if he survives. The Duke of Lorraine and the Swiss had
Beaten him Before,
Twice even when he wasn't so horribly outnumbered. Quite frankly, when Charles went against the Swiss they wiped the floor with his ass repeatedly, in every battle that they fought.
Even with a small tactical victory, the only such victory I could see happening in such a situation given the forces arranged against him, he still has only like 2-3 Thousand Soldiers against the 20 Thousand that the allies against him have.
I also remain skeptical that he would have actually had a Male Child 'if only he had a few more years!' By the time he died he was 44 and had been married 3 times. He only ever had One Daughter. He was hardly some strapping young lad cut down before he got out into the world.
If you want Charles to survive Nancy you'll probably need a PoD that butterflies the battle itself.