This repository contains instructions on how to obtain and use the training data for http://detexify.kirelabs.org. It does not contain the data.
Detexify's training data is stored in https://drive.google.com/drive/folders/0ByuYordD0JBRWXUxRlhEMGtfVVE?resourcekey=0-rYksj_Cs11AMqko9p5swdg&usp=sharing
The database is licensed under the ODbL. This license is also used by OpenStreetMap. A human-readable form of the license can be found at http://opendatacommons.org/licenses/odbl/summary/. I am no expert in database licensing but this looks reasonable to me. Feel free to contact me if you have questions or concerns.