He hasn't said it outright but if you read between the lines it seems like Yiho does indeed like Sion. There's still time for the plot to throw a curveball, but to summarise:
Yiho said Sion sould settle down with someone who cares for him the last time he came to visit, but then when they met after the competition he also said he wanted Sion to break up with Seungwon. He probably wouldn't do that if he didn't have an option in mind or if he didn't care whether Sion was in pain from a breakup with someone Yiho perceives to be an unreliable kid who might change his mind about being with Sion. But who else do we have that would be a reasonable option for Sion in his head? Just himself really.
We can also tell Yiho isn't really the type to go out of his way for people he doesn't care that much about, like with not chasing Seungwon for a contract, and not helping the person who started Sion's fashion line until it was clear it was something that mattered deeply to Sion. But there he is, having done that and also gone out of his way to both stay in Sion's life even if it means waiting for Sion to not be mad anymore, and to find evidence Sion could use to take his abuser down.
So it definitely does read like Yiho likes Sion and has been playing the long game, albeit in an out of touch rich guy type of way.
The other way I can see it go is maybe he's misread his feelings for romantic love rather than platonic though. But I'm pretty sure Yiho at least THINKS he likes Sion.
Sorry for the wall of text! I got overly excited
Wait why’s everyone saying yiho likes MC? He haven’t said anything tho? or was it confirmed in the raws?