Can I use a gift card for Apple Music subscription?

When you redeem an Apple Gift Card to add as Apple Account balance, then that balance will be used before any attempt to use other payment methods, including credit cards. Account balance is always used first.

Your account may still need an additional payment method for the records.

Redeem your Apple Gift Card, App Store Card, or App Store & iTunes Gift Card - Apple Support

Check your Apple Account balance - Apple Support

Add a payment method to your Apple Account - Apple Support

Yes, you can use your Apple Account balance funded with an Apple Gift Card to pay for the Apple Music subscription. You may still be required to have a card on file though to start that subscription and as long as funds are available, it will be deducted from your Apple Account instead of being billed to the card.

• Some purchases might require that you have a credit card on file, even if you use your Apple Account balance to make the purchase.
• Pay for subscriptions like Apple Music, Apple Arcade, and Apple TV. Or pay for subscriptions to apps from the App Store.

https://support.apple.com/en-us/118245

You can use a gift card: https://support.apple.com/en-au/118245

That is how it works in my country. Subscription services through Apple may not have the same requirements worldwide/in other countries. Contact official Apple Support staff if you need official confirmation for your specific situation.

So payment will fail if i didnt have second payment method