On the contrary, the Galactic Imperium has been a clan/alliance since around 2005-2006. They just recently became an alliance on cybernations and have been one for almost a year now. As far as their strength goes, yes it isn't as high as others here, but that's to be expected. They generally like to keep to themselves, and mainly get alliance members from within their clan for whoever they recruit. They don't really go looking around for trouble.
As far as who will win this war, I say Galactic Imperium. Sith Empire's strongest nation is at around 5,000 NS, so GI should be able to handle this fairly easily...
Imperial Sparta