Eartha is from the Old English eorþe — the earth, soil, planet. Her sultry 1953 holiday song "Santa Baby" remains the highest-charting Black-female recording of a Christmas standard.
Eartha 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 Eartha reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.