If my airpods were stolen and someone else connects their phone to them would the location update on find my iphone or does it only update if they are connected to one of my devices?

I think it only updates if they're near one of your devices:

Find the approximate location of your iOS device, Apple Watch, AirPods, or Mac computer using Find My iPhone on iCloud.com. You can locate your device if:

• Find My iPhone is set up on the iOS device or Mac you want to locate.
• Apple Watch is paired with an iPhone.
• The iOS device, Apple Watch, or Mac is online.
• AirPods are out of their case and near one of your iOS devices. Any of your iOS devices can find the AirPods, but they must be paired with at least one of your iOS devices.

iCloud: Locate your device