Could Zuckerberg be jailed as a result of this hearing? For instance, in case of him being previously aware of Europeans data leakage or deliberately lying about it?
"No." is a very short answer for something as complex as could someone become imprisoned.
While the EU parliament doesn't jail people, there are lots of countries that do.
If he admits to breaking the law during the meeting any one of the EU countries could issue an EU arrest warrant for him. Then he would be held within that country to be extradited.
If I was in charge of the British Parliament committee that wants to question him, I would issue an EU arrest warrant for one of the many crimes that are being levelled at Cambridge Analytic with him being part of it. Then question him about it. But I am petty and would want to show that just because he's American he isn't always out of reach.
It's not a complex thing at all. No, there is zero chance, short of stabbing someone on the mean streets of Brussels on the way there that Mark Zuckerberg or anyone else voluntarily appearing before the Conference of Presidents of the European Parliament will be jailed as a consequence.
So, you're saying, Mark Zuckerberg goes and admits to breaking several laws, ones that are criminal in many EU countries, but because he was appearing before Conference of Presidents of the European Parliament no one would issue an EU arrest warrant for those crimes?
The entire assumption is Facebook isn't breaking any criminal laws and Mark Zuckerberg isn't directly linked to those laws.
Chances of going to jail, slim. But it is still in the world of possibilities.