Gary Illyes from Google added to the big crawl budget article he published on the webmaster blog in January 2017 a new question and answer. It basically says that if you disallow a URL in your robots.txt file, then those URLs do not affect your crawl budget.
He added this question and answer:
Q: Do URLs I disallowed through robots.txt affect my crawl budget in any way?
A: No, disallowed URLs do not affect the crawl budget.
He posted last night that he added the Q&A for a former Googler, Pierre Far:
More details:
Forum discussion at Twitter.
