Therefore they could not believe, because that Esaias said again,
Note 11 at Joh 12:39: Joh 12:38-40 could be interpreted as teaching the ultimate in predestination. That interpretation would mean that because of Isaiah's prophecies, these people were never given the opportunity to believe. However, the Word of God makes it clear that "whosoever shall call upon the name of the Lord shall be saved" (Ro 10:13); "behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me" (Re 3:20); and "whosoever will, let him take the water of life freely" (Re 22:17). No one has ever been denied the opportunity to accept salvation (Tit 2:11).
Mr 6:5 says that "he [Jesus] could there do no mighty work, save that he laid his hands upon a few sick folk, and healed them" (brackets mine). In that instance, it is evident that the reason Jesus couldn't do any mighty work was not because He didn't possess the power but because He chose not to use that power against people's wills (see note 2 at Mr 6:5). He couldn't perform the mighty works, because of His decision to be holy and just and to uphold people's freedom of choice.
Likewise, these Jews could not believe because of their choice to reject Jesus (see note 1 at Mt 13:11). The same Greek words ("OU" and "DUNAMAI") are used in Mr 6:5 to say that Jesus "could" do no mighty work as they are used in this verse to say that these Jews "could not" believe. They could not believe, because they chose not to believe. "They stumbled at that stumblingstone" (Ro 9:32) that was Jesus.
Isaiah did not predestine them to this fate, but rather, he saw that very few would receive the report (Isa 53:1) about the Messiah and would therefore be kept from the knowledge of salvation because they rejected Him in whom all the treasures of wisdom and knowledge are found (Col 2:3). This is what Isaiah prophesied, and it came to pass.