Savas’s name day is December 5, the feast of Savvas the Sanctified.
Churches that follow the Old (Julian) Calendar keep the same feast on December 18 of the civil calendar. See everything commemorated on December 5.
The saint behind the name

Savvas the Sanctified
December 5, Venerable, Σάββας ο Ηγιασμένος
Venerable Savvas the Sanctified, born in Cappadocia in the fifth century, entered the monastic life as a boy and became one of the great fathers of the Judean desert. He founded the Great Lavra near Jerusalem, which bears his name to this day, and gathered thousands of monks under his guidance, while defending the Orthodox faith of the Council of Chalcedon.
Also celebrating on December 5
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.