Apple Account
I am not able to add my gmail account in Apple ID.
iPhone 14
If you no longer use the email address that's associated with your Apple ID, you can change it.
Apple support have an article online (link below) that can help guide you:
How to: Change your Apple ID - Apple Support
If you need help with a verification code to sign into your Apple ID online:
How to: Get a verification code and sign in with two-factor authentication - Apple Support