Does Apple Pay require an internet connection?

No, Apple Pay does not require an internet connection. Apple Pay uses NFC technology; it does not use Wi-Fi or cellular technology.

According to CNet, Apple Pay will work even if you put your iPhone 6 into Airplane Mode. Airplane Mode disables both the Wi-Fi and cellular internet.

The answer is yes and no.

Internet connectivity is required for any setup or maintenance of your cards. Once a card has been successfully added to the device, the phone can be disconnected for payments, which is a local interaction between the device and the point of sale terminal.

No, Apple Pay can be used an unlimited number of times while offline since it generates payment information locally as opposed to some other mobile payments like HCE which only allow a limited number of payments in-between getting an internet connection.

Apple Support article: https://support.apple.com/en-us/HT201469