My young BM is still in a 5 gallon container and I am wondering if it can survive outdoors here in Seattle or I need to bring it indoors. I presently don't have a greenhouse.

Seattle is in hardiness zone 8B but it rains a lot in Nov, Dec, Jan, Feb and March. I am wondering if this can be hard on young plants of this variety. 

Most people will say if it's less than 2 years old bring it in. Honestly, I have yet to hear one person say that BM is cold hardy. That's why I don't grow it here in southern Pennsylvania because I would get maybe a dozen ripe figs from it because it takes so long for the fruit to ripen. I stick to cold hardier varieties. Anyways, if this is something that you truly enjoy and cherish than I personally would not risk it and throw it in the tool shed.

Let it go dormant if possible, then put it inside in place with no light to keep it dormant untill spring.

Figo preto and Black Madera are very closely related, Figo might fruit a bit earlier.

Do not put it out. My mother tree(BM) that was kept in my unheated greenhouse
almost got killed last year. This tree is over 10 yrs old. It re-sprouted 2 new shoots
from main trunk close to the ground - all other limbs are dead.

This is very helpful. Thanks!
Paully22, very sorry to hear about your 10 year old tree. I would be very sad if that were to happen to me.
Should I then treat the BM like a citrus, i.e. keep it at a temperature above 50F and avoid having it even go dormant? What about light and humidity? Indoors it does get quite dry in winter.

I have a potted Black Madeira 8-9 years old here in north Georgia. I take it into an unheated garage when the temperature drops below about 25F, otherwise it stays out. We only stay in the low 20's for short periods, though.

Thanks,
Even here it rarely gets below 25F. 21 was the lowest temperature. We had 5 nights between 21 and 25 in the last 365 days. 

Not sure we will get a greenhouse this year. Are there other varieties more susceptible to cold than others that I should bring into an unheated garage? What about I-258, Strawberry Verte, RdB, Smith and the LSU varieties?

I have several cuttings that just rooted about a month ago and are currently in 4 inch treepots. Should these come indoors as well?

I don't know about the cold tolerance of those figs. All my young ones (under 3-4 years) go into the crawl space beneath the house where they stay dormant, but unchallenged by cold.

In Zone 8b, unprotected in winter my Black Madeira dies to the ground then comes back in spring. I lost wood even when I insulated it, so I stopped doing it.
In colder zones, since freezing conditions last much longer, most likely it would not survive the winter.
If you do not want any winter freeze damage, this tree has to be kept at over freezing temperatures (probably in the 40's), during dormancy.

Thanks all! All my young figs are coming indoors this winter