Hii Tarun, 

If you want to choose your carrier as a CA then you can, it doesn't matter that you had PCM or Commerce in your 12th.

As you are asking about it will be beneficial or not, then its all depend on you and on your hard work. But as a CA you will definetely get a good package. 

For CA, first of all you have to appear for foundation exam, this exam conducts two times per year in the month of December or May. Aftet that IPCC which has two groups i.e Group - 1 and Group-2 after clearing both the groups you have to do 3 year training and after all of this you have to appear for final exam. 

I hope you got your answer and helps you to make your choice. 

All the best..