The first thing people think when they think of keeping chickens is of course eggs and they are not wrong that's a really good benefit of them. A good healthy hen can provide an egg almost every day. There are factors that play into that like diet and weather but if you have 6 hens you will have 6 eggs almost every day. If you think how in the world will I use that many eggs, well unlike eggs you get in the store they will keep much longer without needing to be refrigerated. It's not unheard of eggs lasting for up to 6 months. As a chicken gets older egg production will go down so it is important to always have new hens ready but if need be at the end of their life they can provide you will poultry.
Another great benefit is pest control. If you allow your chickens to free range which I highly recommend you do. Then they will eat just about any insect, mouse or snake that crosses their path. Not only do they directly reduce pests like this but as you know if there is less food for things like mice and rats then you also have fewer snakes. Overall they help to keep your home free from pests that can damage it and help keep dangerous ones away too.
The last obvious benefit of keeping chickens is fertilizer. Just like any other animal chickens poop and that poop is fuel for your topsoil. Mixed in with a compost pile it adds much-needed nitrogen back to the soil to help your plants grow. Having that source of fuel for your garden is extremely useful.
Something things to consider before you go out and get some chickens are where to keep them, how many to get and if you are not lucky enough to be outside city limits what are your city restrictions on keeping chickens. You will want an enclosed structure for them to roost at night and something like a wooden box they can lay in. In general, you want 1 nesting box per 3 hens.
A lot of people also don't want a rooster but if you want to be able to keep your cycle going you will need one. Not only does a rooster allow you to hatch your own chicks it also will help to protect the rest of the flock.
Being prepared for a survival situation can be expensive and for some getting started with chickens may seem like a lot but after even just a year you will see how much they really help. Chickens are some of the few things that can help you in your everyday life and in a survival situation.