This is a hard question but I try to answer it correctly. There are female, male and divers* NPC's in Tibia. I counted** all females and will add them at the end of the post. They are 172. When I did the research I already saw there are a lot more "human" NPC's than others, and a lot more males than females. So out of 1063 NPC in total, 172 are female. Even if half of the rest would be "divers", there still would be a lot more males than females.
In conclusion: There are a lot more male than female NPC's.
*Divers means in this case monsters / not obviously male or female.
**I pointed out the females by following facts: The name, the outfit, if TibiaWiki says "her" or "she".
Here are the females:
Alia
Alissa
Amarie
Amber
Appaloosa
Ariella
Aruda
Azalea
Bambi Bonecrusher
Beatrice
Benevola
Bertha
Blossom Bonecrusher
Bunny Bonecrusher
Busty Bonecrusher
Captain Breezelda
Captain Dreadnought
Caramellia
Chantalle
Charlotta
Christine
Chrystal
Cillia
Cornelia
Dixi
Djema
Dove
Eleonore
Emilie
Emily
Emma
Ezebeth
Fayla
Fiona
Gnomally
Gnomargery
Gnomercy
Gnomette
Gnomilly
Gnomincia
Isolde
Jessica
Lee'Delle
Legola
Liane
Maeryn
Malunga
Marina
Maritima
Marlene
Maryza
Meraya
Minzy
Mother of Jack
Namasa
Nina
Norma
One-Eyed Joe
Oressa
Padreia
Paulette
Peggy
Penny
Queen Eloise
Rachel
Red Lilly
Romella
Roswitha
Rowenna
Salbra
Sarina
Satsu
Shanoya
Sharon
Shauna
Sholley
Siflind
Smaralda
Tibra
Trisha
Ula
Ulala
Valentina
Willow
Zora
Agostina
Amanda
Angelina
Artemyth
Asima
Aurita
Barbara
Berencie
Captain Pelagia
Carina
Dane
Elane
Eliza
Fabiana
Fenbala
Flora
Florentine
Gail
Galuna
Guide Davina
Guide Elena
Guide Meruka
Guide Rahlkora
Hanna
Hoaxette
Irea
Iriana
Irmana
Ishina
Ivalisse
Jezzara
Kallimae
Karith
Kaya
Kendra
Lea
Lilly
LIvielle
Lora
Loria
Lorietta
Luna
Lungelen
Lynda
Maealil
Maria
Mirabell
Miraia
Myra
Narsai
Nydala
Odemara
Rose
Rosemarie
Sandra
Sherry McRonald
Shadowpunch
Shiantis
Shiriel
Sigurd
Sorcerer Estrella
Suzy
Talesia
Tamara
Tanyt
Tarak
Tesha
Tezila
Thanita
Topsy
Turvy
Ukea
Ursula
Valindara
Vayns
Velvet
Vera
Wyda
Yana
Zirella
Gladys
Gnomegica
Khanna
Ramina
Saideh
Tefrit
Zethra
(Source https://tibia.fandom.com/wiki/List_of_NPCs)