Which one is better for joining indian defence commercial pilot licence or btech. ?

There is nothing called as Indian Defense Commercial Pilot License. You either join Indian Defense Services or a Commercial Pilot (CPL). With CPL you can be placed in any of the aviation companies as a Pilot. Which one to join is on your preference. If you have a passion of flying jets, and serving

Sakshi better is B.tech both from financial as well as recruitment point of view. Go for B.Tech from some good college/ university and participate in placement drive conducted by defense forces for recruitment. Good luck.