I think, with raspberry pi you can use one csi camera module.
What is with USB cameras? Perhaps you can use a USB hub to connect more than one camera via USB to the pi. I don’t know what you want to do with the images. But you have to consider that the cameras need processing power.
2017-04-27 11:30:26 UTC Tinkerberg - 3 points
since you have totally 4 USB2.0 ports on RaspberryPi 3, you can easily connect e.g. 3 Basler dart (board level) or Basler pulse (with housing) cameras:
For more information on e.g. fast saving of images on RasberryPi 3 refer to:
2017-04-27 11:30:17 UTC mbinev - 148 points