Even though she's only in elementary school, she earns quite a lot of money.
She's still in grade school, but already making a fair amount of money.
earn way という表現は聞いたことがないですね。
この場合は下の例文のように言うと良いと思います。
ーEven though she's only in elementary school, she earns quite a lot of money.
「彼女はまだ小学生だが、かなりのお金を稼ぐ」
elementary school で「小学校」
to earn quite a lot of money で「かなりの額のお金を稼ぐ」
ーShe's still in grade school, but already making a fair amount of money.
「彼女はまだ小学生だが、すでにかなりの額のお金を稼ぐ」
grade school で「小学校」
to make a fair amount of money で「かなりの額のお金を稼ぐ」
ご参考まで！
カナダ 
