According to Vaishnavism, and more specifically in Advaita Vedanta, are Gods other than Vishnu enlightened beings that have attained moksha or are they unenlightened and, if so, does that mean that at some point they are destined to be reborn on Earth again one day to attain moksha?
According to Vaishnavism, Vishnu cannot be said to be enlightened or he cannot be said to have attained Moksha.
This is because he is the Supreme and has never experienced Samsara (except in his human incarnations such as Rama and Krishna).
According to the cosmology of the Srimad Bhagavatam, gods such as Indra, Agni, Varuna, Vayu, Surya, Shiva and Brahma are said to exist in this material universe in Lokas (worlds) above Bhuloka (Earth). Indra, Surya, Agni, Varuna, Vayu and other such gods are said to reside in Suvarloka (heaven; Note that in Hinduism, Heaven is not the final destination to attain unlike in Abrahamic religions), which is two worlds above Bhuloka. Brahma resides in Satyaloka, which is the highest world in this material universe and six worlds above Bhuloka. The description of the material worlds as parts of the body of Narayana is given in Srimad Bhagavatam 2.5.36 and from 2.5.38-2.5.41:
kaṭy-ādibhir adhaḥ sapta
saptordhvaṁ jaghanādibhiḥ || (SB 2.5.36)
Great philosophers imagine that the complete planetary systems in the universe are displays of the different upper and lower limbs of the universal body of the Lord.
bhūrlokaḥ kalpitaḥ padbhyāṁ
bhuvarloko 'sya nābhitaḥ
hṛdā svarloka urasā
maharloko mahātmanaḥ || (SB 2.5.38)
The lower planetary systems, up to the limit of the earthly stratum, are said to be situated in His legs. The middle planetary systems, beginning from Bhuvarloka, are situated in His navel. And the still higher planetary systems such as Suvarloka and Maharloka, occupied by the demigods and highly cultured sages and saints, are situated in the chest of the Supreme Lord.
grīvāyāṁ janaloko 'sya
mūrdhabhiḥ satyalokas tu
brahmalokaḥ sanātanaḥ || (SB 2.5.39)
From the forefront of the chest up to the neck of the universal form of the Lord are situated the planetary systems named Janaloka and Tapoloka, whereas Satyaloka, the topmost planetary system, is situated on the head of the form. (These are the material planets.) The spiritual planets, however, are eternal.
tat-kaṭyāṁ cātalaṁ kḷptam
ūrubhyāṁ vitalaṁ vibhoḥ
jānubhyāṁ sutalaṁ śuddhaṁ
jaṅghābhyāṁ tu talātalam
mahātalaṁ tu gulphābhyāṁ
iti lokamayaḥ pumān || (SB 2.5.40-2.5.41)
Know from me that there are seven lower planetary systems out of the total fourteen. The first planetary system, known as Atala, is situated on the waist; the second, Vitala, is situated on the thighs; the third, Sutala, on the knees; the fourth, Talātala, on the shanks; the fifth, Mahātala, on the ankles; the sixth, Rasātala, on the upper portion of the feet; and the seventh, Pātāla, on the soles of the feet. Thus the infinite form of the Lord is full of all planetary systems.
The above verses, especially the last line of verse 2.5.39 clearly indicate that all worlds between Atala and Satyaloka are material. Hence one experiences birth and death unless one escapes from the material planets (Moksha or liberation).
Kailasa is said to be above Satyaloka and also is a part of the material world. Vaikuntha is above all the Lokas and also above birth and death.
The other gods such as Indra, Varuna, Vayu, Agni, Surya, etc. can be said to still be in Samsara (the material universe) and those in Samsara are said to experience birth and death. But, one important detail to notice is that the Devas such as Indra and so on have drunk Amrita (the Nectar of Immortality). So now, it’s debatable as to whether Devas die or not... But it can surely be said that Vishnu is eternal.