What if my OPT expires before I get a receipt for H1B

My STEM OPT expired May 5th, 2018. I heard, if my company files H1B on time i.e by April 1st, I can get a preliminary cap gap till June 1st in my case, if I don’t get any receipt from USCIS regarding my H1B. But my question is, what if I don’t get any receipt from USCIS even after June 1st. Will I still be able to work? Please clarify.