Yeah, like many Republican gubernatorial candidates in blue states in 2014 Astorino was totally underestimated and was able to creep up on Cuomo and do significantly better than expected. He still lost by 13 points (and has probably guaranteed himself a future nomination if he wants one). Cuomo wasn't going to lose in 2014.
1.He actually lost by 14% 54.2-40.2%
2.The Republican Party has praised him and to be sure Astorino performed better than expected, probably mainly because of the corruption charges leveled at Cuomo (who I can't stand).
That said, consider this:
total votes for Astorino: 1,536,879
total votes for Republicans for the U.S House: 1,554,274
and the Republicans only ran candidates in 18 of the 27 New York congressional districts
Conversely Cuomo over performed the Congressional Democrats
total votes for Cuomo: 2,069,480
total votes for Congressional Democrats: 2,009,444