Tatyana (Татья́на) is the Russian-spelling variant of Tatiana — from the Latin Tatianus, the feminine of Tatius (Titus Tatius was a Sabine king and co-ruler of Rome with Romulus, c. 750 BCE). Born in St. Tatyana Tolstaya — Russian author. "Tatyana" is the heroine of Pushkin's Eugene Onegin (1825).
Tatyana 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 Tatyana reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.