"The seventy men eat chicken."
Translation:I settanta uomini mangiano il pollo.
Well, numbers can behave as nouns or adjectives: in "i settanta uomini" it's an adjective, if you were to call the noun you'd say "il settanta". In most cases it's used while intending a word left unsaid, e.g. "il settanta" can be the bus number 70, or the year 1970, while "i settanta" can mean the age 70-79, or the translators of the first Greek bible (and not the decade 1970-1979 as in English).
All that aside, I was merely pointing out that in "i settanta uomini" the article rules, i.e. the choice of "i" versus "gli", is based on the word following the article, settanta, rather that the word the article refers to, uomini; compare "gli anni settanta" (the seventies) versus "i settant'anni" (the seventy years).
Meat is uncountable, in both English and Italian (if countable, English does have a different plural, "chickens"): however Italian doesn't distinguish between an animal and its meat, so the given translation could be read both as seventy men eating the same chicken (kind of unlikely) and seventy mean eating chicken. An unambiguous translation would be "mangiano del pollo" / "mangiano pollo" (uncountable) or "mangiano un pollo" (countable, so a single chicken).