Does Leaving One Salah Intentionally Make You a Kafir?

Yes. If you did that deliberately, you should repent and enter Islam again, because the Messenger ﷺ says: "That which differentiates us from them (the disbelievers and hypocrites) is our performance of Salah. He who abandons it, becomes a disbeliever." "What lies between a man and (disbelief) is the abandonment of Salah (prayer).” Is there anything clearer than this? Also, the Messenger ﷺ ordered the one who slept or forgot (to pray) to make qadha’ (perform the Salah he missed). This indicates that whoever didn’t pray deliberately, making qadha’ (making up for what he didn’t pray) will not suffice. And if he did perform it, it will neither be right nor suffice.