Your Google Mail is safely stored on Google's servers. Deleting an account from your iPad, while locally deleting messages from the device, will not cause data to be deleted from the server.
When you re-add the account to your iPad, mail messages will be copied back to your iPad.
Add an email account - Apple Support
be aware that some email providers, such as Google, now require the use of App Specific Passwords when accessing mail over IMAP or POP3. If this applies to your email account, you will need to generate a unique password for your iPad - that will differ from your normal Account Password.
If you need to generate an App Specific Password, you’ll need to log-in to your Mail Providers account management webpage - using a web browser - and generate the Password from the appropriate account security page.
More information about Google's App Specific Passwords can be found here:
https://support.google.com/mail/answer/185833?hl=en-GB