You need cables with "amplifier chip" aka "active" cables or "USB repeaters". Otherwise the signal becomes too weak for reliable transmission of video data on such a long distance, and you'll experience frame rate and frame drops issues. You can find recommendation on our web site
http://ipisoft.com/store/hardware, search for "Active USB 2.0 cable". It's an Amazon link, but it gives you an example of what to find in you local stores.
As for USB hub, we generally do not recommend this. Because a hub is connected to a single USB port on PC and thus all connected devices are limited by the bandwidth of this port. Most likely you will only get 2 PS Eye cameras working at 60 fps through the hub.