Only if the campaign's official rules and entry flow clearly grant you that right, and only within the scope actually granted. By default on Meet Your Fan:
- Ticket-raffle campaigns: no UGC is submitted, so this doesn't apply.
- Contest campaigns: the default rules grant the campaign owner a limited, non-exclusive, royalty-free licence to use submitted content for the purpose of running and announcing that campaign. This is not a perpetual commercial licence.
- Media-sale campaigns: the content flows the other way — you sell the media to the fan. The fan does not submit UGC.
If you want broader rights — e.g. to use a winner's submission in an ad — ask for them explicitly, in writing, after the contest ends. Don't try to bury a permanent-commercial-use clause in the entry rules; in several jurisdictions (notably California and most EU countries) such clauses can be voided as unfair terms.