For starters, "Cygnus X-1" is a multi-part "suite" or "song series" that exists in two "books" over two different albums. I can't access Youtube at work, so I'm not sure where your link goes, but I'm guessing you're talking about about "Cygnus X-1, Book I: The Voyage."
On that assumption, and given that "metal" doesn't really have a clear definition, I'll say yes, for the most part, "The Voyage" is "metal."