Gilley's is still around... just not in the same spot. (Not even in the same region.) It's now in Dallas just south of downtown.
TRANSCRIPTION COURTESY OF JOSEPH HOUK - [1979; CW is riding the mechanical bull at Gilley's in Pasadena, while MG and BG look on] (BG) "WOOHOO! RIDE 'EM COWGIRL!!!" (MG) "Okay, explain to me again why we're at Gilley's before 'Urban Cowboy' hit theaters?" (BG) "Do you really want to be here when it's packed like crazy with the movie fans?"