The Turf project is mainly driven by volunteers. However servers, developer fees, prizes, etc. still cost real money.
By supporting Turf you will get some extra functionality that will change over time, but mainly you will support the project and help turf evolve.
You will not get any gameplay-benefits by being a supporter. (no "pay2win")
What you get
-The great supporter sign for everyone to see
-Better league overview, and more...