Colloquially, to be tasty or acceptable to eat; something is reasonably palatable or worth trying.
見た目は微妙だけど、案外食えるよ。
It looks questionable, but it's actually edible/tasty.
このインスタント麺、安いけど十分食える。
These instant noodles are cheap but perfectly edible/tasty.
古くなったパンだけど、トースターで焼けばまだ食える。
The bread is a bit old, but if you toast it it's still edible.
Colloquially, to be able to make a living from something (e.g., a job or art); to be able to subsist on.
彼は音楽で食えるようになったと聞いた。
I heard he became able to make a living from music.
この給料で家族を養って食えるか不安だ。
I'm worried whether this salary is enough to support a family.
フリーランスで本当に食えるかどうか、まずは経験してみるしかない。
Whether you can really make a living as a freelancer is something you have to find out by trying.
Literally, to be edible — safe or suitable to eat (colloquial usage, e.g., whether a mushroom is edible).
そのキノコ、本当に食えるのか確かめないと危ないよ。
You should check whether that mushroom is really edible; otherwise it's dangerous.
生の魚は種類によっては食えるが、調理に注意が必要だ。
Some raw fish are edible depending on the species, but you need to be careful in preparation.
この残り物は見た目が悪いが、まだ食えると思う。
These leftovers look bad, but I think they're still edible.