[{"createdBy":"user1","storyId":1,"viewers":["user3"]},{"createdBy":"user2","storyId":2,"viewers":["user3"]},{"createdBy":"user2","storyId":3,"viewers":["user4"]},{"createdBy":"user5","storyId":4,"viewers":["user3"]},{"createdBy":"user5","storyId":5,"viewers":["user3"]}]

db.collection.aggregate([{"$group":{"_id":"$createdBy","isAllViewed":{"$push":{"$in":["user3","$viewers"]}}}},{"$project":{"_id":0,"createdBy":"$_id","isAllViewed":{"$allElementsTrue":"$isAllViewed"}}}])