Ipad air touch id not working after latest update

See >>> If Touch ID isn't working on your iPhone or iPad - Apple Support

You might try a forced restart of your iPad - as doing so will often resolve an isolated software issue that may occur subsequent to performing a system software update:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On other iPad models: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

I wanted to highlight step 5 in the link added:

1. Go to Settings > Touch ID & Passcode and make sure that iPhone Unlock or iTunes & App Store is on, and that you've enrolled one or more fingerprints.
2. Also it is normal behavior for TouchID to not work after the update at first boot and would require your passcode but in order to verify the TouchID works attempting step will allow you to see if the TouchID sensor is picking up anything.
3. If the TouchID sensor is not picking up anything I would recommend an apple support chat, call or store visit.