Basically yes, says article at Tor.com by Howard Andrew Jones and Todd McAulty.
“I’m a big Traveller fan from way back. What I wanted to expand on here was the reason for Traveller‘s amazing longevity. It was like these Legos: you could build anything with it.”
“I don’t think the early lack of a setting hurt the game in the least. We all talk about Dungeons & Dragons’ famous Appendix N as a way to get additional ideas for your D&D campaign. Traveller was a game system built so you could use your personal science fiction Appendix N and make a campaign out of it.”
“Back when my group played it, our universe was a melange of ideas from authors we liked. There was a lot of H. Beam Piper’s Federation/Space Viking stuff, some Laumer Retief and Bolo gear, and of course Heinlein-style armored battlesuits. Alan Dean Foster’s Thranx and AAnn were running around, or something very like them. You could snap on just about anything. I remember we tried Universe and it was just too science-y and not fiction enough, and Star Frontiers, while it was an amazing world, wasn’t “ours” in the way the little favorite SF-gumbo we’d created felt.”
Also: was Firefly the output of a Traveller game in the early 80s?