How do you say "mentor" in Chinese?
Here are some words which are all related to the idea you are trying to express with pinyin and approximate English glosses:


曼托爾 [Màntuō'ěr] "Mentor - the actual historical figure from whom the English word 'mentor' is derived" (proper name)
老師 [lǎoshī] "teacher" (generic, can be distant, but usually intimate)
師父 [shīfu] "tutor, master, teacher" (usually for something that is practiced)
師傅 [shīfu] "master worker" (usually manual labor)
良師 [liángshī] "good teacher" (rarely used in this sense outside the context of 良師益友 as far as I know)
顧問 [gùwèn] "consultant, adviser" (has the same feel as in English, a bit more distant)
導師 [dǎoshī] "tutor, mentor, teacher, supervisor" (can be both distant and intimate)
指導者 [zhǐdǎozhě] "coach, mentor, counselor" (distant)


On the whole, it doesn't seem that Chinese has a particular term which is a perfect, exact match to the English sense of "mentor". However, the one that feels most right to me is 導師 [dǎoshī], given that I have also seen used the related term 導生 [dǎoshēng] "mentee".

導 [dǎo] means "to guide" or "to lead" with related terms: 指導 [zhǐdǎo] "direction, guidance, supervision", 教導 [jiàodǎo] "teaching, guidance", and 領導 [lǐngdǎo] "leadership, leader".

Given how "mentor" and "mentorship" are used in English, especially in the business sense, 導師 seems the most appropriate. In which case, you could say, "我受他的指導" ["wǒ shòu tā de zhǐdǎo"] "I am receiving his mentorship". This would make it seem that 指導者 [zhǐdǎozhě] might be a better choice for "mentor"; however, 指導者 [zhǐdǎozhě] seems more distant than 導師 [dǎoshī], which feels more intimate.