The word is donc, not dont. This word is usually pronounced [dɔ̃k], but the final
c is sometimes silent in some dialects of French. Furthermore, in Québec French (the only dialect of French where the Anglicism cute exists), some linguists analyze the pronunciation [dɔ̃] as being a separate word which could be spelled don or dont; see Laure’s answer on the previously linked question. The primary meaning of the word donc is “hence, thus, so”. In this context, it doesn’t really connote consequence, but rather adds a bit of emphasis and expresses that the sentence is about a particular situation (TLF §III.A); this is a meaning which is generally pronounced with a silent
c in Québec.
bin is a variant of bien, rarely written this way, evoking a chiefly Québec pronunciation [bɛ̃]. Here, the word is a pure intensifier, meaning “very”.
The subject pronoun on normally refers to an unspecified, generic person: it’s an impersonal pronoun. In modern colloquial French, it’s often used instead of the first person plural (instead of nous), but this is not the case here. Here on refers to the person that the speaker is talking to, as in a second person singular. This is uncommon but not unheard of (I don’t use it myself, but I recognize it). I (city Frenchman) feel that it’s rural and dated; it may be more common in Québec. It is limited to certain circumstances but I have a hard time explaining which. Rose Sene analyzes it as colloquial, and either ironic or affectionate; in this case it’s clearly affectionate. “We” can be used in a somewhat similar way in English, though not in exactly the same circumstances (e.g. a shopkeeper might greet a customer by saying “How are we today?” — “Comment va-t-on ajourd’hui ?”).
To put it all together, this sentence transcribes colloquial Québec French, meaning literally “one is so cute”, or more idiomatically in English “Oooh, how cute you/we look!” or just “Oooh, how cute!”.
When hearing/reading similar uses of ‘dont”, I’ve always thought that the speaker/writer was using “dont” when “donc” might have been a better choice of words: “on est donc mimi comme tout!’
My grandmother’s favorite expression was, “Il est donc valeur d’etre vielle.” My best translation of “donc” in this context is “so” or “such,” as in “It’s such a shame being old.”