The comparative degree usually takes the object of comparison in the genitive, or it may be followed by the comparative particle η. The things compared are generally in the same case.
ἀπεκρίθη Ἰησοῦς καὶ εἶπεν αὐτῷ· ὅτι εἶπον σοι ὅτι εἶδον σε ὑποκάτω τῆς συκῆς, πιστεύεις; μείζω τούτων ὄψῃ. (John 1:50)
Ὡς οὖν ἔγνω ὁ κύριος ὅτι ἤκουσαν οἱ Φαρισαῖοι ὅτι Ἰησοῦς πλείονας μαθητὰς ποιεὶ καὶ βαπτίζει ἢ Ἰωάννης. (John 4:1)