It's "vive", not "viva", in French, and "français" and "anglais" are both masculine, so "franglais" is masculine as well (so it would use "le" as an article).
I'm not American and I really do know what I'm doing when I'm taking le pise.
You'll probably be more likely to hear "viva los Frenchies" from Brits confusing Spanish with French. To us Germanics, you Romantics sound all the same ... or something 8)
It's "vive", not "viva", in French, and "français" and "anglais" are both masculine, so "franglais" is masculine as well (so it would use "le" as an article).