How much power is consumed by a illuminating switch light in the off position? I wired a off-grid solar cabin?

Don't have an exact number, I'd guess at 20mA at 60 volts (half wave to drive a LED) or about 1 watt.

I'd use non-lighted switches, unless you already have them installed.

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If you use an electroluminescent panel (the greenish glow type used in some night lights), the power will be less than 1 mW.

If the light swtich was designed as illuminated, and has an orange glow, it's probably a neon bulb, which typically draws maybe 0.3 mA. So, maybe 40 mW for that solution. If yould doctor the switch yourself, you could put additional resistance in series with the bulb, and it would still give a good glow down to 0.1 mA, at least enough to locate the switch. I think that most illuminated switches that you buy off the shelf are this type, by the way.

A white LED would consume up to 500 mW. The LED is efficient; it's just that tremendous power is wasted in the dropping resistor.

I don't think the neon lighted switches won't kill your batteries, so the consideration would be whether they match the theme of your cabin. Is it rustic?

I would be inclined to use non-lighted switches.

You don't say if you have DC or 120V AC in your cabin. If you have DC, the load would be small, but if you generate AC via an inverter, that would mean the inverter would need to run 24/7. That will cost you a very unnecessary power loss.