Depending on the major and what the app break down for that major is in a given cycle, it could be anything from a tie breaker to a noticeable advantage. There is just no way to tell in advance. The ACT score is very important as is the Math sub-score as mentioned above. Rigor of course-load is also very important, and will depend on the high school and what is available.
She will be given the opportunity to list a 2nd choice major and should do so if there is something else she is interested in. No reason to get hopes up, or to be discouraged. Just put the best foot forward, and of course Purdue and Wisconsin are both excellent options in her range as well.
Good luck.