looks ancient. just curious. 
I know that it is running on a custom version of SMF 1.1.*(19?) As per the footer; Code:
Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines
SMF i think is primarily written in PHP.
https://en.wikipedia.org/wiki/Simple_Machines_Forum
Quote
SMF is written in the popular language PHP and uses a MySQL database.
I'm not entirely sure if Bitcointalk also uses MySQL as primary DB, since this is all heavily modified. I wouldn't be surprised if this is the case though.The new forum however is supposedly using AngularJS. (One could argue that that is also already pretty dated, since Angular 2 basically made JS obsolete (It's on LTS already.).
You can see the progess of the "new" forum software here, https://github.com/epochtalk/epochtalk