Edwards was asked about rumors to that effect during an "Ask Me Anything" on Reddit. He first replied "Talking about it, not able to say a lot yet," and then added "It will focus on Mace Windu."
Assuming that Edwards isn't outright lying (and we have no reason to believe that he is), or trying to make a joke that's not quite translating on the internet, that would seem to confirm is potential involvement in the Star Wars film franchise. There's also no indication of how far away Edwards and Disney are from finalizing a deal.
If Edwards does come onboard for a Star Wars standalone film, he will be the third director named. Godzilla director Gareth Edwards and Chronicle director Josh Trank have both already signed on and been announced as directing standalone Star Wars spinoffs.
Mace Windu is the first character to actually be named as a subject in any of the standalone films so far. Windu, played by Samuel L. Jackson in Episodes I-III, was a Jedi Master who led the order, side-by-side with Yoda, during the waning days of the Galactic Republic.
Star Wars: The Force Awakens, the next film in the Star Wars franchise, hits theaters December 18, 2015.