RES's are very hardy and yes maybe ok for some. I would not , that's about the leaves (SAP) , the pulp of fruit I would use. It's mainly the SAP , even when I trim the tree I have to wear long working gloves because the milky white SAP irrigates my skin. Like people no two turtles are alike and could react differently.
NOTE a fig tree is a FICUS CARICA.
Here's just one of the many sites that talk about it which I found :
https://tortoise.org/general/poisonp.htmlFrom what I found tortoise's can handle them better than aquatic turtles (?) It's like anything how many book's to read before one can make up one's mind especially if half say yes then half say no ? Comes down to a personal call. A friend say's his turtle eats them , you try it and have bad results ? Think a scientist can find anything wrong with anything now a days. Too many other safe plants to use so I will pass on fig leaves (SAP in them)