Furnish is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)

More info here: https://creativecommons.org/licenses/by-nc-sa/3.0/

This means you can use it in your modpack, video, let's play, server, whatever. Just say I made it, link back here and we'll be fine.