Have you added your Gmail account to your new iPad?
Add an email account to your iPhone, iPad, or iPod touch - Apple Support
You should note that Google have changed their authentication requirements for Google Mail mail accounts configured for password authentication - and for non-Google mail clients, may now require use of an App Specific password for each mail client/device.
If this affects you, you will need to generate a unique password for your iPad Gmail account - that will differ from your normal Google Account Password. AOL, Yahoo, Google, Microsoft now all use App Specific Passwords when using anything other than their own email client Apps.
If you need to generate an App Specific Password, you’ll need to log-in to your Google Account management webpage - using a web browser - and generate the Password from the appropriate account security page.
More information can be found here:
https://support.google.com/mail/answer/185833?hl=en-GB