Juanita is mixing orange and blue paint to make yellow paint. She has 5/8 of a gallon of blue paint but she needs 7/8 of a gallon. How much more blue paint does she needs?

Juanita needs 7/8 - 5/8 = <<7/8-5/8=2/8>>2/8 of a gallon more blue paint.

Juanita needs 2/8 / 1/8 = <<2/8/1/8=16>>16 times more blue paint.
She needs 16 * 1/8 = <<16*1/8=2>>2 more gallons of blue paint. Answer: \boxed{2}.