It's a combination of both. I wrote a whole blog about it couple of years back.
Whoa whoa whoa. What do you mean a combination of both? Did CI move all tools, code and assets to the derivative Cryengine 3.x based Amazon Lumberyard or is it still the Cryengine 3.x/Star Engine with bits of Lumberyard spirinkled on it?
If Star Citizen is still using the Crytek based Cryenigne 3.x, source code and putting an Amazon Lumberyard logo on the splash screen and websites, isn't that false marketing or a violation of copyright law?