Here are a summary steps on how to link your BPI Account to GCash:
You can link your BPI Account to GCash App via the the Cash In Button or the Profile Page.
Via Cash in Button
Via Profile Button
Once linking is successful, you will be able to add funds from your BPI bank account to your GCash Wallet.
To learn more about cashing in with your linked BPI account, visit How do I cash in using my linked BPI account?