Check this link on Moneycontrol.
Total turnover is around 6.5lk crore. Exchanges declare only one side turnover data. This is because 1 share Buy from Broker A and 1 sell from Broker B will count as only one transaction on the exchange. So the actual turnover if you would combine all brokerage firms would be twice this.
At first glance, the cash/equity turnover seems to be just 5% of the total overall turnover. But there is an issue, most of the mainstream media usually tout the notional turnover for options. This, in turn, makes this number seem artificially big.
If you buy 1 lot of Nifty call at Rs 50 and sell at Rs 50, you would have generated premium turnover of Rs 7500 ( 75x50+75x50), but the notional turnover of this trade would be > Rs 15lks ( 75x (10800(strike price)+50) + 75x (10800(strike price)+50)). NSE declares the actual premium turnover and you can check it here
Premium turnover of Rs 2800 crores vs notional turnover of 5.5lk crores for Jan 15th.
If you now add up the numbers that Moneycontrol has shared for Jan 15th, it will be around 65000 crores for derivatives and around 30000 crores for stock/equity (50%).
Coming to your questions on how much do top brokers contribute, this isn’t public information. If you look at NSE market pulse
You can see that 40 to 50% of total turnover contribution comes from retail clients (others category) based on the instrument. So all retail brokerage firms turnover will be a portion of this.