My ability to visualize changes depending on the setting and situation I'm in. At any given time my ability is about a 2-4, but when meditating or listening to music with my eyes closed and relaxing and visualizing for fun, it becomes more like a 4-6. Personally I don't think I'm very good at visualizing, I'm never more better than just decent at it under optimal conditions.

As far as lucid dreaming goes, I haven't actually put effort into having lucid dreams for well over 6 to 7 years now. On average, I have between 20 and 60 lucid dreams naturally over the course of the year without ever trying/intending to lucid dream. That average goes up when I make an effort to practice greater awareness and mindfulness in my life (in general), which I wind up doing on and off every few months.

Considering some people (very rarely) aren't even capable of visualizing or otherwise seeing anything with their mind's eye at all, I'm not sure how strong the link between visualization ability and lucid dreaming is going to be. If anything, I'd guess that what has more of a causal effect is the fact that people that practice visualization in the first place are going to be more likely to practice lucid dreaming too, and they're going to put greater effort across the board into the things that actually have a stronger correlation with greater numbers of lucid dreams... like practicing greater awareness and mindfulness, getting more experiences of lucid dreams under one's belt and becoming more familiarized with the state of consciousness, recognizing dream signs and recurring themes and aspects of one's dreams, etc.