Does spending mana from a Gilded Lotus count as colored mana for devotion?

Devotion is calculated by counting the colored mana symbols (the {W}, {U}, {B}, {R}, {G} symbols) that appear in the mana costs of permanents you control on the battlefield. This is defined in CR 700.5: "A player's devotion to [color] is equal to the number of mana symbols of that color among the mana costs of permanents that player controls."

Gilded Lotus is an artifact with a mana cost of {5} — a single generic mana symbol with no colored symbols at all. This means Gilded Lotus contributes zero to your devotion to any color, regardless of what colored mana it can produce.

The mana Gilded Lotus produces is completely irrelevant to devotion. Devotion never looks at mana abilities, activated abilities, or what colors of mana a permanent generates. It only reads the printed mana cost symbols on permanents you control.

Example: You control Nykthos, Shrine to Nyx, a Gilded Lotus, and a Gray Merchant of Asphodel (which has {3}{B}{B} in its cost). Your devotion to black is 2 — counting only the two {B} symbols in Gray Merchant's mana cost. Gilded Lotus adds nothing to that count, even though it can tap to produce {B}{B}{B}.

If you want to increase your devotion, you need permanents with colored mana symbols printed in their mana costs, not permanents that merely produce colored mana (CR 700.5).