Yes, a commerce student can become pilot in India. You don't need to be from a science background to pursue a flying career. The Directorate General of Civil Aviation (DGCA) allows students from any stream science commerce or arts to apply for a Commercial Pilot Licence (CPL) provided they meet all required conditions. However students with non science backgrounds may have to clear certain extra subjects before starting pilot training.
A commerce student who wishes to become pilot must pass Physics and Mathematics at the 10+2 level. If these subjects were not taken in school they can still study them through the National Institute of Open Schooling (NIOS) or any recognized board as an additional qualification. This ensures eligibility to apply for DGCA exams and CPL courses.
The cost difference is minor. The main expense for pilot training comes from flight hours simulator sessions and DGCA fees not from academic subjects. However a commerce student might have to spend some extra money on tuition or online courses to learn basic Physics and Mathematics. This small cost (around INR30,000-INR60,000) is much lower compared to the full pilot training cost which ranges between INR35-INR50 lakh in India.
So a commerce student can become pilot without any major disadvantage. The extra cost is minimal and mostly limited to completing science subjects. With strong determination proper guidance and DGCA approved pilot training institutes like Pilot CET commerce students can achieve their dream of flying high and building a successful career in aviation.