If you check out the Leafs’ CapFriendly page, you’ll see that they currently have six defensemen considered to be on their NHL roster with contracts: Morgan Rielly, Jake Gardiner, Ron Hainsey, Nikita Zaitsev, Travis Dermott, and Connor Carrick.
So, more or less the same mix of guys that ended with the team last year, minus Roman Polak.
Then there are some guys who have NHL contracts, are listed as still having “minors” status, and who might compete for a spot as the Leafs’ 7th D: Justin Holl, Martin Marincin, Calle Rosen, Andreas Borgman, and Igor Ozhiganov.