"But the angel of the Lord came down into the oven together with Azarias and his fellows, and smote the flame of the fire out of the oven; And made the midst of the furnace as it had been a moist whistling wind, so that the fire touched them not at all, neither hurt nor troubled them...
And Nabuchodonosor heard them singing praises; and he wondered, and rose up in haste, and said to his nobles, Did we not cast three men bound into the midst of the fire? and they said to the king, Yes, O king. And the king said, But I see four men loose, and walking in the midst of the fire, and there has no harm happened to them; and the appearance of the fourth is like a son of God....
And king Nabuchodonosor answered and said, Blessed be the God of Sedrach, Misach, and Abdenago, who has sent his angel, and delivered his servants, because they trusted in him; and they have changed the king’s word, and delivered their bodies to be burnt, that they might not serve nor worship any god, except their own God."
Daniel 3, LXX
From the context, it seems to me that it was an angel, not Jesus personally. Even though "angel of the Lord" can be seen as Jesus.
The term the pagan king used (a son of god or a son of gods) does not change the meaning. The words of Babylonian kings are not our creed. He simply expressed that there is some divine looking being. He did not identify him to be the Jewish Messiah or one of the Trinity, he did not have such knowledge.