Is "et al." used as a singular or plural subject?

Question

When referring to multiple authors by using the name of the first author and *"et al."*, is it correct to grammatically treat this as one person or multiple persons? > Gamma et al. **are** saying in **their** text... vs. > Gamma et al. **is** saying in **his** text...

Answer 1

If multiple authors have contributed to a text and you are not engaging with one author's arguments/ideas to the exclusion of the rest, I would go ahead and treat this as multiple persons, i.e.  Gamma et al. **are** saying in **their** text.

If, on the other hand, you are reading something like a Cambridge companion that features multiple articles by multiple authors, I would only cite those authors that you are actually engaging with.