For smaller, independently produced films, a Best Picture nomination is of major help at the box-office.
Consider Louis Malle's intimate drama, “Atlantic City” (1981), which was nominated for five awards, including the Best Picture Oscar, after being cited as best film of the year by the prestigious National Society of Film Critics.
There's no doubt that the movie gained from its reissue after the Oscar nominations were announced in early 1982. Opening on April 3, 1981, “Atlantic City” completed its run before the end of the calendar year with $3.3 million in domestic rentals.
After the nominations, however, the movie was rereleased and grossed another $1.7 million, a rather small amount in absolute terms but about one-third of its total domestic grosses.