Can i plug a usb keyboard to my iphone while it's connected to my mac? I need to backup my iphone 5s but the screen is completely broken, it's all black and the touchscreen doesn't work so i need a way to control my phone from a keyboard to back it up from icloud that recognises it.

Is there anyway to do it?
Not a USB keyboard afaik, but this lightning keyboard has been reported to work with iPhones.

There's a thread on the apple discussion board by someone in the same situation as you that used the keyboard linked above as part of their backup process.