Did the Jews know the prophets spoke about the Gentiles being reached?
The Jews were aware that the prophets, including Isaiah, spoke of Israel being a light to the Gentiles. However, they did not expect it in their own generation, sharing Jonah's reluctance to go to Gentile cities. So yes, they knew the prophecies but resisted their fulfillment.
Les teaches that the Jews knew the prophets spoke of the Gentiles being reached, specifically that Isaiah spoke of Israel being a light unto the Gentiles. However, they had no idea they were to go to the Gentiles in their own time; they thought it was for a future generation. Their attitude was like Jonah's, who would rather walk the plank than go to a Gentile city. So when God told Ananias that Saul would bear His name before the Gentiles, this was unheard of in Jewish culture, and Ananias likely swallowed hard. Up until that time, God had been dealing only with Israel.