In marketing and communications, impact refers to the purportedly meaningful results of a public good campaign or program.
It’s meant to distinguish the value of such activities from “income” and other purely monetary measures, ie., revenue, profit, etc.
Thus, a philanthropic org commissions “impact studies”.
In advertising, impact is…
“That quality in an advertisement which strikes suddenly against the reader’s indifference and enlivens his mind to receive a sales message”
– Raymond Rubicam