One of the options you have is to split your 7,000k territories to one user list into groups of say 500 territories and list that into your RLS dataset. So that should give you per user 14 rows in this dataset.
When there are more than one row per use the QuickSight RLS logic will be an OR so it should be able to cover your case. There is work to do compress your list and provide comma separated values in the Territory field.