Not without manually changing data files. I know some people have done it but there are some side effects to doing so.
I have modified my Room_Types to allow for 10 Bars, 3 Main Dining Areas, 2 Storage Rooms, 2 Employee Break Rooms, and 10 Locker Rooms totaling 72 total employees(including other rooms such as Restroom, DJ, Pool etc). I have different room setups I've play tested such as 10 Bars with no Main Dining and a couple of other setups to check if breaking even on money was possible(which it is).
My main layout is 1 Office, 2 Storage Rooms, 7 Locker Rooms, 1 Kitchen, 1 Restroom, 3 or 4 Bars, 3 Main Dining Areas, 4 Dressing Rooms, 1 Sound Booth, 1 Pool, 1 Aux Office, 1 Security Room, 1 Entrance, 1 Parking Lot, and 1 Game Room.
My PC has 32GB of System Memory and 8GB of Video Memory running Windows 7(I won't use Windows 10 or 11 as I value my privacy). The only problem I've encountered is after about 1 year into the game and after you've hired 60 to 70 people, the game WILL in fact use ALL 32GB of my system memory as well as ALL 64GB of my Paging File. I will get a windows system warning that my memory is Full after playing for about 3 to 4 hours. I try to combat this by saving, then exiting the game to allow the Game and Windows to dump my Page File as well as 'release the extended memory' the game has used. Waiting for about 5 minutes before reloading the game. This seems to work fine. Then about 2 to 3 hours later repeat saving, and exiting. Nothing else is modified in the configuration files or in any other '.txt' file in the Data Folder or Runtime folder. It is all about how many people pictures are in the game. In one play through, I've maxed out at over 250 NPC's active in the game. That play through I have to exit and reload quite frequently.
So yes, having more than 55 employees works just fine for me. With the 'saving and exiting' work around.
Mr. Fluke needs to look at how he is allocating and reserving memory for graphics in this game. But I still love this Game!!!