Zoey is the more common modern spelling of Zoe — from the Greek zōē (ζωή), meaning "life." The y-ending feels more American and contemporary; the e-ending (Zoe) is closer to the original Greek.
Zoey entered the U.S. Today it sits in the U.S. top 40, ahead of the Zoe spelling.
Zoey 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 Zoey reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.