early-15c., "abounding in, copious" (of God's grace); mid-15c. "flowing to" (of liquids), both senses now obsolete, from Old French afluent (14c.) or directly from Latin affluentem (nominative affluens) "abounding, rich, copious," literally "flowing toward," present participle of affluere "flow toward," from assimilated form of ad "to" (see ad-) + fluere "to flow" (see fluent). The especial sense of "abounding in wealth or possessions" is from 1753.
<a href="https://www.etymonline.com/word/afflux">Etymology of afflux by etymonline</a>
Harper, D. (n.d.). Etymology of afflux. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/afflux