Earlier quoted context omitted.
My guess is they're counting code from existing packages used to create the site. So for example, if they used Java, that line count is including the lines of code found in the JDK. I see no other way of getting to such a large number.
I don't see it approaching that even with the lines of code for their existing packages. For instance, this is old and out of date, but you could extrapolate a ballpark estimate out of it... looks like back in 2007 or so JDK was about 6 million LoC ( http://cr.openjdk.java.net/~darcy/OpenJdkDevGuide/OpenJdkDev... ). Even if it increased tenfold since then, it's barely making a dent in that 500 million LoC number.
I kept reading the article and on the last you find this gem:
According to one specialist, the Web site contains about 500 million lines of software code. By comparison, a large bank’s computer system is typically about one-fifth that size.
That to me suggests the number is bogus, because it is so obviously a quote from someone who has no idea what they are talking about.