Learn French: Nous avons les données, donc nous sommes prêts. - We have the data, therefore we are ready.

Yes, you could absolutely say Nous avons les données, alors nous sommes prêts. Both words show a consequence. Donc (therefore/so) feels a bit more logical and formal, which fits well with a sentence about "data". Alors (so) is slightly more casual and conversational.

Is the word données (data) related to the verb donner (to give)?

Yes! Une donnée literally means "a given" (a fact or piece of information given to you). When used in the plural as les données, it translates to "the data". It is a feminine noun, though here you just see the plural article les.

Why does the word prêts end in an "s"?

Prêt (ready) is an adjective, so it has to match the subject it describes. Since nous (we) is plural, we add an "s" to make prêts. If "we" refers to a group made entirely of women, you would use the feminine plural form: prêtes.