What are the consequences of declaring a Muslim an apostate if he said that God and Satan are on the same level, and then sought forgiveness for that?

The phrase mentioned is an explicit insult to Allah, Glorified and Exalted be He, and it is undoubtedly an act of disbelief (kufr). Its utterer is deemed a disbeliever if they say it willingly and intentionally. The claim of ignorance is not accepted when it comes to insulting Allah, Exalted be He. Specifying an individual as a disbeliever only occurs when the conditions for declaring someone a disbeliever are met and its impediments are absent, such as being an adult, sane, acting out of free will, and not excused by ignorance or misinterpretation. However, if they were coerced or their words could be interpreted in another way, this prevents ruling them a disbeliever. Insulting Allah or His Messenger is clear disbelief, both outwardly and inwardly, regardless of whether the insulter believes it to be forbidden, considers it permissible, or is heedless. The matter of declaring someone a disbeliever is not to be taken lightly, and it is the exclusive domain of scholars, judges, and rulers, after the conditions are met and the impediments are absent. There are three stages in disbelief that expels one from the fold of Islam: identifying the act as major disbelief, then declaring the individual who committed the act a disbeliever (which is the prerogative of judges), and then not definitively asserting their eternal damnation in Hell after death, while applying the rulings of disbelief to them in this world.