"imap.gmail.com" server does not respond

Have you enabled IMAP in your Gmail account?

https://support.google.com/mail/troubleshooter/1668960?hl=en#ts=1665018

iOS: Unable to send or receive email

http://support.apple.com/kb/TS3899

Can’t Send Emails on iPad – Troubleshooting Steps

http://ipadhelp.com/ipad-help/ipad-cant-send-emails-troubleshooting-steps/

Setting up and troubleshooting Mail

http://www.apple.com/support/ipad/assistant/mail/

Server does not allow relaying email error, fix

http://appletoolbox.com/2012/01/server-does-not-allow-relaying-email-error-fix/

Why Does My iPad Say "Cannot Connect to Server"?

http://www.ehow.co.uk/info_8693415_ipad-say-cannot-connect-server.html

iOS: 'Mailbox Locked', account is in use on another device, or prompt to re-enter POP3 password

http://support.apple.com/kb/ts2621

iPad Mail

http://www.apple.com/support/ipad/mail/

Try this first - Reset the iPad by holding down on the Sleep and Home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons. (This is equivalent to rebooting your computer.)

Or this - Delete the account in Mail and then set it up again. Settings->Mail, Contacts, Calendars -> Accounts Tap on the Account, then on the red button that says Remove Account.

 Cheers, Tom 😉