Yes, that's exactly what he was thinking while singing that song, in fact he even had his eyes closed so he could imagine seeing Nirma so his voice could fill more feelings into the song.
Atif Aslam responded by saying, "It is a very good thing that our SENIORS are liking our work and are appreciating us." and he also added that he will get married when he finds the right person. As far as I remember Atif talked about his crushes in an interview in which he said, "I have had crushes but nothing serious. Probably long time back, I had crush on bollywood actress Sonali Bendre, she was my favorite"
source: http://www.jinnahsequaid.com/film-actress-nirma-proposed-atif-aslam/