Yes, their influence count towards matching. 

My Clan expels inactive members who have not notified Chief of Elder why, but invite them to re-join when they can be active again. That way we have a better chance of avoiding mis-match in CvC events as their would influence count but they are not earning points in the event.

As far as I am aware Plarium does not remove dead accounts so their influence still count in kingdom events and can be a pain especially in KvK if they still have troops left.