Where abouts in the world are you? I'm going to stick my neck on the line and say Ibera and a boy. I understand why you are caring for him but to be honest he would be better off in an outdoor enclosure than being kept inside. Are you sure he's wild? In the photos he demeaner seems very carm which I wouldn't expect from a wild tortoise. I have kept tortoises smaller than this in an outside enclosure with excess to a greenhouse all year in the uk so honestly he'd be fine outdoors. They tend to eat weeds and plants mostly have a look at this link for ideas on what weeds are safe. Diet and healthy growth
Grape vine leaves are perfectly good food too. When it gets cooler he may want to hibernate which probably in your part of the world he will do quite sucessfully in a sheltered area of soil.

Jason