They have stated they have him lined up to narrate, yes. It's a little ways down on the kickstarter page description.
Here's the roster of voice talent that have said they will be involved:
Gary Owens - Narrator from SQ4 and SQ6, voice of Space Ghost, Laugh-in, and many many others in a long and distinguished career.
Rob Paulsen - Pinky from Pinky and the Brain, Yakko from Animaniacs, Raphael the Ninja Turtle, and multiple characters from Monkey Island among many other characters he has voiced.
Robert Clotworthy – Jim Raynor from StarCraft 1 & 2, Senator Evran & Supreme Chancellor from Star Wars: The Old Republic, and Narrator of The History Channel’s Ancient Aliens series, Big Bang Theory, etc.
Ellen McLain - GLaDOS from Portal 1 & 2, Overwatch from Half-Life 2, Administrator from Team Fortress 2, Witch from Left for Dead 2 and many more.
John Patrick Lowrie - Sniper from Team Fortress 2, Sword Control from Halo Reach, Citizens from Half-Life 2 and author of Dancing with Eternity.
I must say, the Gary Owens thing kind of clinched it for me. SQ5 always felt like something was missing since he wasn't there. Also recently, the SQ2 VGA remake from Infamous Adventures came out. They did a GREAT job with it and I enjoyed a few of the tweaks they did, but the narrator guy was trying, and mostly failing, to do a Gary Owens impression. Everytime he was speaking, I was doing a much better Gary Owens impression in my head.
**In case it wasn't clear, this IS NOT a new Space Quest game, it's a new "SpaceVenture" that will have all the DNA of SQ, just no Roger or other characters/locations. Apparently the SQ IP is owned by Activision, and they aren't interested in selling at the moment (or are asking a stupid amount of money, not sure which). Maybe if this campaign succeeds and the game makes a bunch of money on release, they can get Space Quest back and make a new one?