I would say no earned run, based on the following from OBR:
10.16 EARNED RUNS AND RUNS ALLOWED
An earned run is a run for which a pitcher is held accountable. In determining earned runs, the official scorer shall reconstruct the inning without the errors (which exclude catcher’s interference) and passed balls, giving the benefit of the doubt always to the pitcher in determining which bases would have been reached by runners had there been errorless play. For the purpose of determining earned runs, an intentional base on balls, regardless of the circumstances, shall be construed in exactly the same manner as any other base on balls.
(a) The official scorer shall charge an earned run against a pitcher every time a runner reaches home base by the aid of safe hits, sacrifice bunts, a sacrifice fly, stolen bases, putouts, fielder’s choices, bases on balls, hit batters, balks or wild pitches (including a wild pitch on third strike that permits a batter to reach first base) before fielding chances have been offered to put out the offensive team. For the purpose of this rule, a defensive interference penalty shall be construed as a fielding chance. A wild pitch is solely the pitcher’s fault and shall contribute to an earned run just as a base on balls or a balk.
The "defensive interference penalty shall be construed as a fielding chance" suggests you assume that play should've be an out.
Thus from here you reconstruct the inning as if this play was an out on the runner going home.
After that play, it's whatever happened with that many outs with runners on whatever bases.
If you reconstruct that the kid who hits the single actually hits, then he hits a single.
If additional runs score after two outs, they are unearned to the pitcher. They are earned on the scoreboard, however...
