You need to show the money at the bank, if you are going to be your brother’s sponsor.
Depending of what he will study is how much you need to have in your bank; they want to make sure that you have enough money to pay one full year of tuition. I sponsor before; for English school you need $4,000 - $6,000 and for college student $16,000 -$20,000 and I am sure is much more in some schools.
They include other living expenses, no matter that you will provide for him; they will ask you for the same amount.