How To Use A Visa Gift Card On Playstation 4. Go to the website to register the card. Use the gift card to load your PSN wallet.

You have to use it as a credit card and most online stores wont let you use multiple credit cards on a single order for various. If by Gift Card you are referring to Prepaid cards to top up your wallet then unless the other accounts can buy though another account the answer is generally no. Set up a payment method on Playstation Store.
One wallet is created for each PlayStationNetwork master account.
Prepaid cards add funds to a PlayStation. You use it in the exact same way you would use a credit card. Go to the website to register the card. Set up a payment method on Playstation Store.
