This is a SOLAS issue + local rules apply for certification of the vessel for use (ie also, waivers can be applied for).
However, in a typical situation: usually, the orange, red or yellow powered "lifeboats" you typically see are intended for passenger use. A typical large lifeboat and winch system can handle 150 passengers. The overflow passengers are expected to follow trained crew into Inflatable life rafts. They are usually in the white plastic looking drums; most are on the the lifeboat boarding deck, plus some other areas of the ship. The plastic drum usually splits open and self inflate on deployment.
Each lifeboat is actually very expensive equipment to just having sitting around. But what's really expensive is the profit reduction due to the removal of a balcony suite cabin or two for each lifeboat added to the design. This is one reason you see a single row of lifeboats, rather than a double rows on cruise ships.