I have seen some leftists stand by this statement as entirely true, and I have also seen some leftists dismiss this idea as cope on the part of liberal Zionists who dislike Netanyahu/Likud (and who would like to delegitimize both Likud and Hamas together).
The following are some relevant articles that support this idea:
https://www.timesofisrael.com/for-years-netanyahu-propped-up-hamas-now-its-blown-up-in-our-faces/amp/
https://theintercept.com/2018/02/19/hamas-israel-palestine-conflict/
https://www.thenation.com/article/world/why-netanyahu-bolstered-hamas/
What is clear is that Israel has allowed Qatar to fund Hamas on numerous occasions without much interference. However, whether Israel has ever actually funded Hamas specifically with Israeli money is not as well-established (although many of the people who support the general “Israel propped up Hamas” idea definitely imply that this has happened). So as a corollary question, how important of a difference is this?
My understanding is that the more clerical Muslim Brotherhood were funded as a less political alternative to Islamic Jihad and the PLO (which was at this time pretty radical, leftist, and committed to the destruction of Israel), and Hamas began as a branch of the Muslim brotherhood.
And then we demolished the MB in Egypt, because it had the temerity to be slightly more left-leaning than the last military dictatorship. And now we're mopping up what's left of them in Gaza.