How to upgrade using gcash?

i wany to pay thru gcash,is it possible?

No, that is not possible, if you are talking about this app ?

• A mobile wallet app that lets you instantly pay bills, buy load, send money, shop, and more – all in the safety of your own home!

You can't use GCash app as your Payment method for the App Store.

See -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card. If your card is not accepted as a paymenf method, you need to contact your bank.

You need to contact your bank, they can find out who (name, address & account number) has collected the amount from your bank account, and when.

My iphone have no space for memory,and i want to add and buy 50Gb

1.

Try to free up iPhone device storage see this Apple articles below:

If you need more space for an update on your iPhone, iPad, or iPod touch

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

How to check the storage on your iPhone, iPad and iPod touch

How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

2. 

See -> What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

See also the following Apple articles:

Upgrade to iCloud+ -> Upgrade to iCloud+ - Apple Support

iCloud+ plans and pricing -> iCloud+ plans and pricing - Apple Support

• Accepted payment methods for iCloud+ upgrades include credit cards, debit cards, and your Apple Account balance. If you don't have enough available funds in your Apple Account balance to complete your upgrade, you'll be charged the remaining amount. Apple Store gift cards aren't accepted as payment for upgrading iCloud+.

How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)

Manage your iCloud storage -> Manage your iCloud storage - Apple Support