No, Mellonta Tauta is not a goth band, because they play Dream Pop/Ambient, while goth music consists of Gothic Rock and its derived genres, like Deathrock, Darkwave, Ethereal Wave, and Coldwave.

However, they do have a significant goth influence and even have some goth songs in their repertoire, like "Remain the Feeling" and "Pull the charriot".

If you want to dive into the goth music scene, some of the bands that might appeal to you if you enjoy Mellonta Tauta are Autumn's Grey Solace, Cocteau Twins, and Love Spirals Downwards.