iCloud storage upgrade

If by iTunes card you mean a gift card, then that is perfectly possible.

Payment methods that you can use with your Apple ID - Apple Support

Redeem the gift card to your account, and the price of the upgrade will be deducted from your account balance automatically.

You will need to keep enough gift card balance on your account every month to cover the monthly subscription cost however.

Unfortunately this can't be, the reason is that it's a subscription based and not a one time payment, so you will need another form of payment like CC.

I didn't know that iTunes card balance can be used in iCloud storage purchase, thanks fr the info.