""Ocho billón.""
Geez, they can't even get *that* right. "Eight billion" would be "ocho billones" in Spanish, since one would need to use the plural.
Actually, if one wants to get technical, "eight billion" should be translated as "ocho mil millones" (literally, "eight thousand million") since in Spanish-speaking countries the word "billón" refers to "a million million," not "a thousand million." This is exactly like the traditional use of the word "billion" in Great Britain, in which "billion" was used for "a million million" and the word for "a thousand million" was "milliard."