How many kids does Satan have?

Answer 1

In a literal sense, none. In a spiritual sense, billions.

To further enlarge on this, Satan is a spiritual being and so cannot have children in the human physical sense.

His spiritual children are all those who have been deceived by him into believing his many lies, of whom there are undoubtedly billions both living and dead.

The following passage addressed directly in dialogue to the Jewish religious leaders of Jesus' day illustrates some of the relevant criteria for being a spiritual child of the devil. Jesus did not apply this term either lightly or with error. Such would also apply to any others who meet the criteria illustrated both here and elsewhere in scripture.

John 8:41-47 (King James Version)41Ye do the deeds of your father. Then said they to him, We be not born of fornication; we have one Father, even God.

42Jesus said unto them, If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me.

43Why do ye not understand my speech? even because ye cannot hear my word.

44Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

45And because I tell you the truth, ye believe me not.

46Which of you convinceth me of sin? And if I say the truth, why do ye not believe me?

47He that is of God heareth God's words: ye therefore hear them not, because ye are not of God.

Additionally:

His are the "children of disobedience": [Eph.2:2].