Yes, you can but there is no point of doing B.Arch if you are already a civil engineering student and according to my opinion, better to complete your B.Tech in Civil first and after that give Gate exam as this will give you entry in higher studies (M.E/M.Tech) and you can also try in PSUs if you clear it with required score.
So decide well.
Good Luck!!!!
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile