While the outcome of Petrovs' actions was the best it could have been, he literally had one job and he failed to do it. Did he face any kind of punishment from the Soviet army/state? Did he receive any commendations?
He didn't actually fail at anything.
After establishing that launches are few in number and detected only in one limited area he reported up to chain of command that it is false alarm in the early warning system (so called Oko or 'Eye' - several satellites watching main ICBM sites in the mainland US).
Commander of Soviet Missile Defense Forces Votintsev arrived at the command post, confirmed that it is a false alarm and reported so to the Soviet minister of defense Ustinov.
Notably enough, a very similar incident happened during the test run of the system just two months earlier. After which the system was disabled for additional testing and upgrades. September incident confirmed the problem and another round of improvements was scheduled, so 'Oko' was finally accepted into the military service only in 1985.
It is one of the cases when journalists really overblown a rather mundane story for the shock value. There was never a real danger of Soviet launch in response to that. Petrov didn't have an authority for it anyway. System was in testing and therefore wasn't considered reliable. And there were plenty of people above Petrov who were in position to countermand his decisions.
As far as commendation goes - initially he was supposed to be commended for his actions during this incident, but investigative commission found enough irregularities in his command, so commendation was buried. But he wasn't reprimanded too.
Sources:
Does anyone have any technical details regarding how the Soviets (or the Americans, for that matter) would have been able to suspect, or have a reasonable idea, that this was a false-positive alert?