I’ve had several people ask me this question and yes, it does fit in the sleeve. When you first slide the keyboard in the sleeve it is a nice snug fit. Not too snug but probably more than you would like. But after a day of use it slides in there no problem (as seen in the video).
If you’ve read some user comments and questions on Apple’s website for the Apple Leather Sleeve both some users and Apple people have said that it does not fit, which is causing even more confusion. It clearly does.