EDIT: made one simple small Q&A brochure with all answers i could find from David Braben regarding Elite, if you know any other interview or Q&A session let me know and i will update it
Elite Dangerous. Q&A with David Braben.pdf
Well, you can take a look at this one between Scott Manley and David Braben: https://www.youtube.com/watch?v=T28ZWKyadUc
It is however not mainly a ED Q&A, they talk about all sorts of things (space mostly). Nevertheless, I found it quite interesting to listen to. Scott Manley is primarily known for his videos on Kerbal Spaceprogram.