Does iOS 7 cellular tethering limit the number of WiFi clients?
The thing about these limits is that the carriers and iPhone models are all different. For instance, the iPhone 5 should theoretically be able to handle up to 14 connections, but both AT&amp;T and Verizon limits it to 5. As far as I have understood, it is hardware-limited, and therefore it is not affected by iOS version.

I have started on a list which anyone may suggest an edit to if they come up with new information. Feel free to comment as well.




iPhone 3GS supports up to two peers combined through USB and Bluetooth-tethering. 1 
iPhone 4: 1, 2

AT&amp;T-version supports up to three Wi-Fi peers, three via Bluetooth, and one USB peer.
Verizon-version supports up to five Wi-Fi peers, three via Bluetooth, and one USB peer.

iPhone 4S supports up to five Wi-Fi peers. Unconfirmed
iPhone 5 supports up to five Wi-Fi peers. (AT&amp;T and Verizon confirmed 3)
iPad 3rd gen is currently unknown.
iPad mini is currently unknown.
iPad 4th gen is currently unknown.



Please note that Apple have not disclosed any of these limitations, they simply state: 


  The maximum number of supported connections may vary depending on your carrier or iPhone model.


Apple have also stated in an article about all iPhone-versions and the third-gen iPad that:


  Depending on your wireless carrier and, the maximum number of Wi-Fi connections may be limited to three at one time.