"Oscar winners bring in 7.6 percent higher box office return on average than nominees that don’t win, according to IBIS world. On average, winners of Best Picture earned 57 percent of their total revenue before the nominees were announced, 27 percent once they were nominated and more than 15 percent after winning an Oscar. Nominees that didn’t bring home the gold earn just 5 percent of their total take after the awards show."
That means that, for example, “Extremely Loud and Incredibly Close,” which has grossed $31 million so far (not very much by Hollywood standards), would end up making about $36.5 million if it wins and $32.6 if it does not. So about an extra $4 million at stake.
It is not quite clear to me if those percentages are right. For winners we have 57 + 27 + 15 = 99, which is pretty close to 100% and it could just be a rounding issue. But for losers, it only adds up to 89%. Since they only get 5% after the awards show, the earlier numbers have to be higher than 57 and 27. If the earlier 95% has a 57/27 ratio, it would be something like 64% and 31%.
The article also discusses the economics of the cost of ads and ratings issues.