Anybody can perceive him as gay if they want him to be.

You're speaking of the coding of his character. Coding does not equal implication. Because this Vautrin from this other book is not the Wriothesley from Genshin Impact. Many such cases of course where other pieces of fiction and life as we know it tend to impact other forms of fiction and how we consume it has the tendency of being influenced by our bias.

Let's just touch on a basic. Coding and implications.
Implication = "Man, I really love fries!" Character B said. (B saying they love fries so generally IMPLIES that they must also love curly fries)

Coding = Character B's shirt has an overwhelming number of curly fries as a design on it. (B wearing said shirt makes you THINK that they must love curly fries)

This is the difference between the two.

Wriothesley also has staple-like attire similar to that from webtoons that tend to include a male and female lead (romantically most of the time) which is something I have seen multiple people associate him with along with what you have just told me.

He can be gay if you want him to be. I think he's queer because that's what he makes me think.

Am I right? No. Am I wrong? Also, no.
Sexuality isn't a personality trait though. He is or he isn't, he's still a character that appealed to me and I enjoy very much regardless.