Darla is an early-20th-century American name — a variant of the English endearment "darling" — also linked to Darlene. Darla Sherwood — Nemo's would-be tormenting niece in Pixar's Finding Nemo (2003); her arrival heralded by Bruce's "Fish are friends, not food" reverse; Finding Nemo won the Academy Award for Best Animated Feature (2004) and grossed $940 million worldwide on a $94 million budget. Darla Moore (born 1953) — American businesswoman; first woman featured on the cover of Fortune magazine (1997); the Darla Moore School of Business at the University of South Carolina is named for her.
Darla 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 Darla reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.