The settings are currently hidden in-game and to enable tracking you have to do a workaround.
- In Steam, right-click the game - Properties - Launch options
- Type in: -TobiiEye <scale> <range>
Scale options: 0.2 to 6.0
Range options: 0.1 to 1.0
Default settings are 1.0 and 0.7.
- Run the game in Steam VR mode and then you can enjoy tracking like before in helmet view.