I'm in the video game industry working on AAA console titles, and the last game I worked on sits right around a million lines for the runtime executable, and maybe another 1-2 million for all the supporting toolchains.

I worked on a game once that was about 4 million lines, and it had continuously evolved for about a decade at that point.

If the 500 million line comment is true, it probably counts all the lines in all the supporting documentation, xml configuration files (which could be huge), etc.

I'd bet my life's savings that it's not actually half a billion lines of executable code.