As a name in its own right, Ellie has been used since the late 20th century and has risen rapidly into the U.S. top 35.
Ellie 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 Ellie reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.