tl;dr version: This is a complex issue which requires an understanding of the exact terms under which God gave the Jews the land of Israel in the first place. In short, they probably don't have any divine claim on it until the Messiah explicitly gives it back to them.
According to the Biblical record, the land of Israel was originally promised to the descendants of Abraham, which was later established through Jacob/Israel and entrenched according to the Mosaic Law. While not explicitly spelt out, this appears to be part of the same covenant referenced in the Qur'an, and to which God says "My covenant does not include the wrongdoers."
There is no shortage of evidence (again according to the Biblical record) of the land of Israel being taken away from the Jews in response to their disobedience, and returned to them when they returned to righteousness. The Hebrew Bible basically ends with God exiling and scattering them until the Messiah comes to re-establish the proper state of Israel.
So just because the Jews during the time of Moses were considered worthy of claiming the Holy Land (as referenced in Al-Ma'idah 20-21) doesn't mean that modern Jews are. Many Jews still consider themselves in exile and don't even consider the current state of Israel to be part of this divine covenant; until the Messiah comes and gathers all the Jews, rebuilds the Temple, and reigns over them with the authority of David's line, it's just a secular state that happens to be in the same physical location.
From a Muslim perspective, one interpretation is that the Jews are no longer entitled to the land of Israel at all, if only due to their outright rejection of at least two major prophets (one of whom was their promised Messiah), and that God has given it to the Ishmaelites instead (which could either mean Arabs in general, or Muslims in particular given that Muhammad (Peace Be Upon Him) was a direct descendant of Ishmael). As Ishmael was also a son of Abraham, it could be understood that the original Abrahamic covenant applied to him as well as Isaac (through whom the Jews claim their right). This interpretation is somewhat supported by the Qur'an, which says, "the most worthy of Abraham among the people are those who followed him and this prophet, and those who believe."
Another possible interpretation, which is more in line with Sheikh Adwan's claim, is that the land of Israel is still the promised land of the Jews. However, this would still be contingent of them being able to reclaim it according to God's will, which was traditionally one of the roles of the promised Messiah. From an Islamic perspective, while it is difficult (although probably not impossible) to argue that any modern Jew who has rejected the Messiah (i.e. Christ Jesus) outright can have any claim to the promised land, this could well apply to any who either choose to follow him during his return (which, insofar as he hasn't returned yet, doesn't really apply to the modern state of Israel), or those of Jewish descent who have already embraced Islam (or, at the very least, accepted Christ Jesus as the Messiah).
A third interpretation is that, until the Messiah returns to set things straight and explicitly give the land of Israel to those it is promised to (be they Jews, Muslims, or other), it's just a secular land like any other with no divine claims to worry about.