[iOS]If I delete my data and start Mario Kart Tour from the beginning again, will my Gold Pass benefits carry over?

If you erase your save data by using the Start Fresh option, you can still use your Gold Pass benefits (200cc, ability to receive additional tour gifts, etc.). From the Apple Account you used to purchase your Gold Pass, go to the Gold Pass purchase screen and tap Complete Purchase and you can continue using your Gold Pass benefits without any extra charge.

Note: If you use the Start Fresh option, your tour gifts, challenge progress, and items received will all be deleted.
For details on starting fresh see: Is it possible to restart Mario Kart Tour from scratch after linking a Nintendo Account?