No. It will not affect the credit of the merchant account holder. However, if that business is unable to pay back the chargeback amount, and ends up losing their merchant account, it could eventually end up on the credit report if they fail to ever pay it back.
A chargeback would never affect the person making it. It's a right that cardholders have. The onny exception would be if a person is making a fraudulent chargeback, which could technically result in the theft of the item being purchased. Even in this case, it would be a civil/criminal matter and not anything to do with credit.