According to textual research, Empresses in the Palace has a real historical background (it did exist in Yongzheng period). But there is no Zhen Xuan in real history. Her prototype is a concubine of Yongzheng, Nugulu, and she is indeed the mother of Qianlong. But she's not Zhen Xuan. Before Yongzheng ascended the throne, she had entered Qin Yong Palace and was called "Gege". After Qianlong succeeded to the throne, she was honored as the empress dowager. Qianlong died in forty-two years (1777) at the age of 86.

The fight for affection must be true. As for the others, I think only the names are the same.