You run like hell, all the while hoping the ATM security camera did not catch your face as you committed attempted murder, and that he does not tell the cops to check the ATM records to find out who used it just before that person shot him. (Might try claiming you gave some bum permission to use your card and are waiting for him to bring the card back to you. Probably won't work, but you can try.)
The guy is advancing towards you, circling - which means he is probably trying to cut off a line of withdrawal (I hate calling it a "line of retreat"). All he has done so far is speak to you - and none of the words he used would meet any definition of a threat, let alone a threat of violence or the proverbial threat of imminent death or serious bodily injury.
Tell him stop in that "firm, clear voice." Make the universal "stop" hand gesture. Possibly say something about not wanting to hurt him if he does not stop - but there is some risk in making threatening statements.
He is slowly advancing towards you, which means he has not yet cut off your line of withdrawal - so get off the "X" and start withdrawing. Be sure to look around as much as you can to prevent yourself from being blindsided by some possible partner. While you are withdrawing, figure out where places of safety might be - solid obstacles you might put between yourself and the advancing man. Watch out for corners, and for places with deep shadows, and stay away from them.
Then, after following this advice either completely or partly, explain why the %#$* you want to shoot someone.