cannot set up gmail on ipad. says cannot connect to imap server. any suggestions?

Are you able to load your Gmail account in Safari?

This Google article might help you out -> Setting up Google Sync with your iOS device

If you don't want to use Google Sync (If you're not sure, I'd recommend using Sync), you may want to check this doc out -> Gmail iOS App

Try backing up, doing a reset, and re-putting everything back on, or try reseting the entire "Mail" app in settings

-Darren