Does Gaea's Cradle count a creature token when producing mana?

Gaea's Cradle reads: '{T}: Add {G} for each creature you control.' The key phrase is 'each creature you control,' and tokens are permanents that are creatures — they fully count toward this total (CR 111.1, 111.7).

There is no rule that distinguishes tokens from non-token creatures for the purpose of counting creatures you control. A token on the battlefield is simply a permanent of the specified types, subject to all the same rules as any other permanent of those types (CR 111.7).

The number of creatures — and therefore the amount of mana produced — is calculated at the moment Gaea's Cradle's ability resolves, not when it is activated. So any creatures that die or enter the battlefield between activation and resolution can change the result (CR 601.2, 605.3a).

Example: You control Gaea's Cradle and four Saproling tokens created by Tenderness Thornweald. When you tap Gaea's Cradle and the ability resolves, you add {G}{G}{G}{G} — one green mana for each of those four tokens.

Tokens do cease to exist when they leave the battlefield (CR 111.8), so they will no longer be counted after that point, but while they are on the battlefield and you control them, they count fully for Gaea's Cradle.