The following four gate names are agreed upon by scholars:
al-Jihaad (struggle for the sake of Allah)
ar-Rayyan (for those who fast, it means "quencher of thirst")
As for the rest below, there is some disagreement among scholars
al-Kaazimeen al-Ghaiz ("those who control their anger")
al-Aafeen an an-Naas ("those who forgive people")
ar-Raazeen ("those who are content")
al-Ayman ("on the right", for those who enter Paradise without judgment)
Ibn Hajar says that there might also be gates of al-Dhikr (remembrance of Allah) and al-Ilm (knowledge).
As for using them as names, the first four are used as names as in Salaat, Jihaad, Rayyaan and Sadaqah.
Tawbah is an uncommon name, but I've seen it used for both girls (mostly) and boys.
For the gate of al-Kaazimeen al-Ghaiz, the name from this is Kaazim, also spelled Kadim, Kadhem, Kazem, which means "one who controls his anger".
For the gate of al-Aafeen an an-Naas, the names relating to it are Aafeen, Afuw,
As for ar-Razeen, the names are Raazi, Raazia, Rizaa, Rizwaan, Marzia.
For al-Ayman the names are Ayman, Yumna, Yameen.
For al-Dhikr the names are Zaakira, Zaakir, Zikraa.
For al-Ilm, the names are Aalim, Aalima, Aleem, Aleema, Allama.
If you have questions about any of these names feel free to ask.