Canonicity in the Star Wars universe is, as of April 2014, determined by a working group comprised of representatives of Disney and Lucasfilm known as the Lucasfilm Story Group.
The primary change made is that the old canon system (G-Canon, T-Canon, etc) has been nuked from orbit and only the original six feature films (the Original Trilogy and the Prequel trilogy, as seen in the 2011 Blu-ray Edition), Star Wars: The Clone Wars TV show, Star Wars: The Clone Wars film and Star Wars: Rebels TV shows are considered to be part of the official Star Wars canon.
"While Lucasfilm always strived to keep the stories created for the EU
consistent with our film and television content as well as internally
consistent, Lucas always made it clear that he was not beholden to the
EU. He set the films he created as the canon. This includes the six
Star Wars episodes, and the many hours of content he developed and
produced in Star Wars: The Clone Wars. These stories are the immovable
objects of Star Wars history, the characters and events to which all
other tales must align."
By definition, the other properties that were originally deemed to be "G-Canon" and "T-Canon" (the Star Wars Radio Dramatisations, Star Wars Holiday Special, earlier Star Wars: Clone Wars TV Show, Ewoks films, Star Wars : DroidsTV show and Star Wars: Ewoks TV show), along with any deleted scenes, making-of documentaries, behind-the-scenes documentaries, concept art books and previous versions of the scripts are now all considered to be "Legends" properties.
Taken at face value, this press-release would seem to include proclamations from Mr. Lucas and anyone else associated with the making of the films. Although their words are interesting and certainly deserve notice, they aren't one of the "immovable objects" to which everything else is subordinate.