FIA president Jean Todt also confirmed the news, saying it will be announced officially "in coming days".
In the US, however, Haas said Ecclestone and the FIA are yet to inform him.
"We haven't been notified by the FIA, but Bernie is kind of half formula one, so I'm sure what he says goes," he is quoted by the Associated Press.
But Haas, who admitted he decided to enter F1 to raise awareness of his highly successful tool machine business Haas Automation, admitted the delay in getting the 2015 entry approved is a worry.
"We needed to know about two months ago," he said.
"If Mr Ecclestone says that we're accepted and the FIA issues us some kind of notice in the next few weeks, then we can entertain 2015. But if we lose another month, I don't think we could do it."
F1 supremo Ecclestone admitted he is not sure Haas will "turn up" in 2015.
"It's easy to put the entry in," the 83-year-old told British broadcaster Sky.