未だに + [verb ない-form] 未だに + [verb て-form] + いない 未だに + [verb て-form] + いる 未だに + [noun] + だ
未だに means "still", "even now": a situation has gone on up to now, longer than you'd expect, and hasn't changed. It goes before the predicate, which is most often a negative, きごう〜ていない or きごう〜ている. It is also written in kana, いまだに.
"Still hasn't" is きごう〜ていない or the plain negative, not the past: the not-happening goes on now.
まだ also covers what is only just beginning or not over yet – "there's still time", "it's still early". 未だに can't, because nothing there is overdue.