>Is it known what percentage of cravings a person has in a typical day for tobacco is the result of actual withdrawal vs habit?

This is a great research question! It can be helpful to think about craving, withdrawal and habit as “motives” for smoking (in other words: what drives people to use). Some other motives include: automaticity (smoking mindlessly), coping with negative emotions, affiliative attachment (seeing cigarettes as a ‘friend’), among others. There is a lot of research looking at how these motives relate to each other and to smoking (for example: https://journals.sagepub.com/doi/full/10.1177/2167702620978614) but there is still a lot of work to be done.