I have come across the following hadith:
"I entered Paradise and saw a damsel with tan skin and beautiful dark (red) lips, so I asked Jibreel, 'Who is this?' And he replied, 'Indeed, Allaah, The Exalted, knows what Ja'far ibn Abi Talib desires, and that is tan skin and dark (red) lips, so Allaah created this for him.'"
I was wondering, what is the authenticity of this hadith? I have heard that Al-Albaani declared it fabricated in his Silsisat, but I read in his revision of Sunan An-Nasa'i, as hadith 3380, narrated from Anas, that it was authentic. I am confused, what is the final authenticity of this hadith?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

The hadeeth number 3380 that was reported in the book Saheeh wa dha’eef Sunan An-Nasaa'i authored by Al-Albaani is not the same hadeeth that you mentioned in your question and which Shaykh Al-Albaani classified as fabricated in Silsilat al-Ahaadeet Adh-Dha'eefah.

The wording of the hadeeth that was reported in Sunan An-Nasaa'i is as follows:

“Anas narrated that the Prophet conquered Khaybar, and we prayed the Fajr prayer there before the morning twilight appeared, then the Prophet got on his mount (horse), and Abu Talhah also got on his mount, and I mounted behind Abu Talhah on the same horse. The Prophet rode through the streets of Khaybar and (I rode so close to him) that my knee touched the thigh of the Prophet ; the wrapper got aside from his thigh, and I could see its whiteness. When he entered the town, he said, 'Allahu Akbar (Allah is the Greatest), Khaybar shall face destruction. Whenever we approach near a (hostile) nation (to fight), then evil will be the morning of those who have been warned.' He repeated this thrice. The people came out for their jobs, and some of them said, 'Muhammad (has come).' (Some of our companions added, 'With his army.') We conquered Khaybar, took the captives, and the booty was collected. Dahyah (a Companion) came and said, 'O Allah's Prophet! Give me a slave girl from the captives.' The Prophet said, 'Go and take any slave girl.' He took Safiyyah bint Huyayy. A man came to the Prophet and said, 'O Allah's Prophet! You gave Safiyyah bint Huyayy to Dahyah, and she is the noblest lady of the tribes of Quraythah and An-Nadheer, and she befits none but you.' So the Prophet said, ‘Bring him along with her.’ So Dahyah came with her, and when the Prophet saw her, he said to Dahyah, ‘Take any slave girl other than her from the captives.’ The Prophet then manumitted her and married her. Thaabit asked Anas, 'O Abu Hamzah! What did the Prophet pay her as dowry?' He said, 'Her freedom was her dowry, for he manumitted her and then married her ... While on the way, Umm Sulaym dressed her for marriage (ceremony), and she sent her as a bride to the Prophet at night. So the Prophet was a bridegroom, and in the morning, he said, 'Whoever has anything (food) should bring it.' He spread out a leather sheet (for the food), and some brought dates and others cooking butter. So they prepared a dish of Hays (a kind of dessert). And that was the Waleemah (the marriage banquet) of the Prophet .'” [Al-Albaani classified it as Saheeh (sound)]

Allah knows best.