Well. bhai Punia is among one of the biggest gotra but i stick to the point that Godara, Beniwal have more population than Punia or any other Jat Gotra.
I said that i didn't included Jatt Sikhs. If we include Jatt Sikhs than Sangwan can't be compared with Gill gotra.
Jatt Sikh have four major over spread gotra's i.e. Sidhu, Mann, Brar and Gill and can overlap any Hindi Jat gotra (in population ) except a few like Godara, Beniwal, Punia, Malik.
Yes Bhai, i know Sindhu and sidhu are totally different ( originally were JAT only ).
I also know that Sidhu gotra is most populated amongst Sikhs and you will wonder that Sidhu gotra have sub gotra too. One of my friend ( Sidhu ) got married to a Sidhu girl ..... surprizingly i asked .... what's the matter ...... and then i come to know the fact that Sidhu's have sub gotra's too. Her bride was Sidhu ( Brar ) and he himself was Sidhu ( Sidhu ). But both were Sidhu.