Been there many times. For starters, tell her to never EVER look at the batter's face, never look them in the eyes. That intimidating look the batters always give the pitcher, that is EXACTLY what it does to almosty every 8 year old.
The batters NEED her to look into thier eyes, the NEED to know they have been seen and noticed. It is a HUGE confidence builder for the batters. DONT DO IT. It is an advantage the pitcher needs to keep for themselves.
When you have the ball in that circle YOU control EVERYTHING. The batter doesnt swing the bat, the runner doesnt leave the bag, NOT UNTIL YOU SAY ITS TIME.
Have her focus on the catcher's mask and never look at the batters. Aftyer a few innings the batters will realize she couldnt care less about them and it will show in their ability.
Its part of THE PITCHER / BATTER 'THING'.
Get her back in control of her game and you will see a different pitcher.
Hal's advice here, to me, is key especially for a young pitcher. My daughter (age 10) knows she is not to address her "fans" in the stands or any other outside source while pitching. She only looks at the catcher. She has to know that the game goes at her speed and she is directing the game from the circle. The game definitely speeds up at 10U and she needs to be prepared mentally to handle that. Good luck!