would like to use an apple gift card to pay for increase in my cloud storage

Redeem the card if it is the right kind. Your Apple ID balance will be used first to make payments.

What type of gift card do I have? - Apple Support

Redeem your App Store & iTunes Gift Card - Apple Support

How App Store and iTunes Store purchases are billed. Click here --> https://support.apple.com/HT201359

"Which payment method is charged?

When you buy items or pay for subscriptions, Apple automatically attempts to charge your payment methods in this order:

1. Apple attempts to use your Apple ID balance to cover the full amount.

2. If you don't have Apple ID balance, you don't have enough to cover the full amount, or an item cannot be paid for with Apple ID balance, Apple attempts to charge your primary payment method (typically a credit or debit card, but varies according to country). The primary payment method is at the top of the list in Settings on your iPhone. You can control which payment method is at the top of the list.

3. If there's a problem with the primary payment method, or if the primary payment method can't be charged for the full remaining amount, Apple attempts to charge your other payment methods in order from top to bottom. If none of them can be charged, Apple may try again.

deatrice176 Said:

"would like to use an apple gift card to pay for increase in my cloud storage"

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What Type of Gift Card?:

Apple Gift Cards allow you to purchase most items, whereas iTunes Gift Cards are for iTunes. So, if you have an iTunes Gift Card, you wouldn't be able to use it with the rest of Apple.