Usages of ni
Note: the subject marker が is more appropriate than は in this context. The subject of the sentence is たくさんのユダヤ人 (many Jewish people), and in this case, が is typically used because it is introducing new, non-contrastive information.
Where きっと expresses a strong belief or confidence that something will happen or is the case, 確か に often additionally implies that the speaker has evidence or reasoning to support the certainty, or has personally verified the fact.
ushiro mo iriguchi ga arimasu.
ano eiga wa, nijikan goro kakarimasu.
eiga wa, gogo niji gurai ni hajimarimasu.
eiga wa, gozen niji goro ni hajimarimasu.
eiga wa, gozen niji gurai ni hajimarimasu.
Note that here it would also be possible to say 向こう の コウモリ, meaning the bat over there.
The particle combination には is often used to emphasize the topic, especially when discussing existence, characteristics, or attributes related to that topic. It can be translated as as for or regarding, but often it's simply used to stress the topic being discussed.
tenki ga ii to, sanpo ni ikimasu.
You cannot use と here, as the consequence is neither habitual nor uncontrollable.