Continuous state of 煙草を吸う, how to conjugate plain and te-form (polite/short)

Question

たけしさんは煙草を吸いません。 ---> Takeshi will not smoke. ---- (1)　　
たけしさんは煙草を吸わない。 ----> Takeshi will not smoke. (the short form of the above). ---- (2)　　

たけしさんは煙草を吸っていません。 ----> Takeshi is not a smoker. ---- (3)　　
たけしさんは煙草を吸っていない。 -----> Takeshi is not a smoker. (the short form of the above). ---- (4)

Hopefully those four are correct. If so, then the sentence "I like people who do not smoke" should be (from using (4)):
煙草を吸っていない人が好きです。

However, Genki says it's 煙草を吸わない人が好きです which, when using (2), sounds like it's saying "I like people who will not smoke."

Answer 1

たけしさんは煙草を吸いません。
Takeshi will not smoke.

I think you might be confused about the meaning of 'will'. The English 'will' is tricky and has two very different meanings that we tend not to notice. You seem to be treating it with a volitional meaning, but the 'will' expressed by the plain form of a verb in Japanese can only be future tense. So the translation you give is valid but in means Takeshi will not smoke in the future. It does not mean that Takeshi refuses to smoke.

However, for your context you should be using the present tense interpretation of the plain form, which happily translates to "Takeshi does not smoke", which is just what you need to say "I like people who do not smoke".

I'd like to say something about the meaning/validity of 煙草を吸わない人が好きです but to be honest, I'd probably get it wrong. Choice of conjugations in relative clauses can be quite subtle and I don't feel qualified to comment.