My friend has an iPad Air, do they need to update the software before November 3, 2019?

iPad Air is not affected, and also no iPad is affected that has Wi-Fi only. Affected devices are:

iPhone 4s

iPhone 5

iPad 2 (CDMA Cellular only)

iPad 3 (Cellular only)

iPad 4 (Cellular only)

iPad mini 1st gen (Cellular only)

See this for more information: https://support.apple.com/en-us/HT210239

The update that is out is only for the iPhone 5. This would not affect their device anyway. It fixes an issue with GPS on the iPhone 5.