I think a little bit of fig as an occasional treat would be okay. Just don't feed any fruits as part of the main diet due to their sugar levels. It's like candy.
Here is info from the Greek Tortoise Care Sheet about their diet needs:
Greek tortoises spend much of their time grazing on edible landscape. For this reason, it is an excellent and healthy idea to offer weeds such as Dandelion, clover, plantain, hawksbit, cat's ear, wild strawberry, and thistle. When these items are not available like during the winter months, they can be replaced by dried, bagged organic herbs. These can be found online. Store bought greens like collards, mustards, kale and turnip can be offered sparingly. Commercial diets such as Mazuri are excellent for helping the tortoises maintain good weight but again should be offered only in moderation. Calcium supplements in the form of cuttle-bone are wonderful additions to their diet. The tortoises will gladly nibble on them as they feel the need and take in appropriate amounts.