Gyda is from the Old Norse guð (god) or guðr (battle). Gyda Eiriksdottir (9th c.) was the Norwegian noblewoman who refused to marry King Harald until he had united all of Norway under his rule — Harald swore not to cut or comb his hair until he had done so. Her demand effectively created the Kingdom of Norway.
Featured in Snorri Sturluson's Heimskringla.
Gyda does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Gyda reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.