Your original problem is that you are using Python version 3 and according to this posting the
thread module has been renamed
_thread in Python 3.
After correcting that issue you state in your comments that the program still doesn't work.
I suspect that is because you never execute the
thread.start(pushButton,()) line of code because the previous block of code is an infinite loop,
while True: will run the subsequent block of code forever and the thread.start will never get executed.
I recommend that you move the
tread.start line of code before the
while True block. I also recommend that you put some sort of
time.sleep into your
pushButton routine otherwise your will continuously output either "on" or "off" very quickly.
I would try:
import RPi.GPIO as GPIO
if GPIO.input(17) == 1: