The amount of money you make off of twitch depends on the cost of the subscription to your twitch and how many subscribers you have.
Twitch also takes 50 percent of the subscription price that is paid to you so you get half of the money and twitch gets the other half of the money for the subscription.
There are three subscription levels on twitch which range from $4.99, $9.99 and $24.99 so you would take the amount of subscriptions you have and take half the money out of it for twitters fees and portion and you get the other half and that is the amount of money you make.
Some people can make thousands of dollars per month from twitch while others may only earn $200.00 per month to $500.00 per month.
It all depends as the more subscribers you have on your twitch account the more money you'll make.