Is “et al. [1]” used as a singular or plural subject?
Et alii means "and others", so it would make sense to treat Gomes and others as plural. Note that et al. is not used for et alius ("and another"), since Gomes et alius is barely or not at all shorter than Gomes and Samuel: it is only used when there are three or more authors in total.
On the other hand, Gomes et al. can stand metonymically for the text by Gomes et al., which would be singular; so a case can be made for treating it as singular.