Are the gods athanatos in some texts?
They sure are!
Philódēmos employs the word καθανατοις (kathanatois) in lines 69-70 of On Piety.
In line 1139, he refers to ἀθάνασιαν (athanasian) or "immortality".
I was under the impression that the gods were "incorruptible" and not "immortal."
On Piety gives us at least three alternatives to ἄφθαρτον (aphtharton).
He quotes Epíkouros as writing "...that it is possible even for many eternal and immortal gods to exist" (lines 65-70). Obbink translates "eternal" from [2] ἀΐδιος (áidios). Then, in line 693, he uses the word [3] διαινωια (diainōia), from "δια-" and "αινωια", roughly, "for forever".
Though, they are also "incorruptible" as per KD1 and the Epistle to Menoikeus.