> Is QT actively being maintained, and is KDE able to incorporate (or better - steer) those changes

The relationship between the two orgs is currently healthy. They have different needs, but collaboration innl the Free Qt Foundation has been productive of late and hasn't hit major roadblocks.

The annual Qt Contributor meetup and KDE events are semi-regularly co-located. KDE people help maintain a few of the modules, or rank as biggest external contributors.

It's a relationship that always deserves active maintenance but has been holding steady overall.