I live in GA and I want to know is there anyway a aunt can get joint custody with the mother of the child if the father is in prison and I care for him just as much as the mother.

No there are no extended rights to other family members with exception to some states that recognize grandparents rights.

The best you can do is try to get along with the mother. Good Luck.

No, there's nothing legally you can do (other than to get along with the mother as pointed out). Some states have grandparent rights but no state has any other extedended family rights (the government would be over stepping the line if they try for much more).