The 59-year-old, who is the longtime partner of Hudson's mother Goldie Hawn, stated that he simply couldn't wait for the arrival of the Nine star's child with Muse frontman Matt Bellamy.
"It's fun having babies once again," he declared to People. "We just really like that. And it's fun to watch them grow. It's fun to see what they're grasping. I think secretly we're all hoping for a girl."
Speaking of Bellamy, whom he met for the first time over Christmas, Russell added: "He's really fun. We all enjoy him. We understand what Katie sees in the guy. He's a great guy."
Hudson already has 7-year-old son Ryder from her marriage to Black Crowes singer Chris Robinson.