Thoughts on only using cables...

You're always gonna get advised (when it comes to weightlifting anyway), to incorporate compound lifts, especially the main ones like squats, deadlifts, bench and OHP.

However, nothing wrong with using machines and equipment like cables to get your workout in. As long as you're challenging yourself and shifting heavy weight, your strength will increase (being in a caloric surplus helps).

The bit about gaining or maintaining is about your eating habits rather than using cables at the gym.

In my opinion, if you are careful about exercise selection and the cable machine offers sufficient resistance for your exercise selection, then you can accomplish almost everything you could with free weights. At least you can if you have a wide enough variety of cable machines to choose from. And the fact that you get a constant resistance over the full range of motion gives cable machines an advantage over some free weight exercises.

As for strength, that really depends on what you mean by "strength". Do you mean being able to lift heavier weights as time goes by? Then sure you can increase strength, just make sure you're doing a well structured program incorporating progressive overload into your cable-machine workouts.

Cables are good like everyone is saying some free weights is good for a well rounded workout. The exercises tend to be easier on the joints too. I just started doing cable skull crushers, and I would say I'm gaining just as much strength and size as I was using barbell. Just stay away from machines. Pure evil. Strength gains will definitely come as long as you use proper form and weight. Cables are a big part of my workouts.