[8pla.net]

Watch the whole video, it's a very good, but Sophia's admission to using ChatScript starts at 11.56

It shouldn't come as too much of a surprise, ChatScript is used by one of the most advanced social humanoid robots.  After all, ChatScript is forked in Hanson Robotics GitHub repository.  Now, Sophia's own words, confirm it, "I use a layered chatbot starting with a frame based code in ChatScript, then a little machine learning and a neural network as a backup. "   So, go ahead and enjoy this really fascinating video.  Neil deGrasse Tyson and his side kick, Chuck, are amazing and funny, and really entertaining.

[Don Patrick]

It's nice to have that confirmed. Until 2016 it has also used AIML, but it looks like now it's just ChatScript. When AIML was in use I also spotted something like neural network weights linking to it, but all they seemed to do is influence which file of scripted responses had preference for specific topics.
https://github.com/hansonrobotics/hr-solr
https://github.com/hansonrobotics/ChatScriptNLP

[frankinstien]

It's funny but Sophia sounds more robotic now than before, did they lose the human voice that use to talk through her? Well, I guess that admission of using Chatbot kind of says it all...

[8pla.net]

Sophia said she uses a layered chatbot, and mentions three layers. ChatScript on the first layer, then.machine learning on another layer, and a neural network on another layer.