My brother needs to get temporary custody of his 5 children in the state of Georgia. He is being told that temporary custody orders are not offered in the state of Georgia.

Welcome to AMHD. Last time I heard, they are. Better find another source of information.
Here is some material: Georgia Child Custody Law

It might also help us help you if you gave more details of the situation. As the link George provided points out, temporary custody is assigned pending a hearing on full custody. So a court process has to be started to determine custody an a request made to change the current custody situation.

Who has the kids now? What custody arrangement is currently in place? Is it court ordered? Why does he need to change the current custody?