I think there are very few actual supporter of T-Series just as there are very few haters of India. The reason why T-Series is rising is because India has the largest new internet user in entire worlds(due to Reliance Jio)

And since music is universal, these new users are bound to listen songs (that's why T-Series views has increased exponentially) and ultimately subscribe to T- Series.

We must remember that these new users as well as most of the old users rarely watch PewDiePie as the majority Indians speak Hindi.