Or will it have, by the time GT5 releases? 

So first of all lets guesstimate how much Polyphony gets from each copy of GT5:P sold. For a full price game, the developer gets roughly $20. That is 33% of the retail price. GT5:P retails at $40. So 33% would be roughly $13. In Europe it retails at £25. If we use the same percentage, Polyphony get roughly £8 ($16). If we assume that from Japan it is somewhere in the middle, on average Polyphony gets $15 per copy sold. Also remember Polyphony are first party.

Sony reported that GT5:P had sold 2.23M, including downloads (this was a while ago though). That would produce revenue of roughly $33.5M. 

Now, GT5:P can't of cost much to develop, because all of the cars and tracks will be used in GT5 anyway. How much do you think GT5 costs to develop? It has beautiful graphics, millions (hundreds) of cars and 50+ tracks. It takes a lot of time to design a car and track for GT5. Although, there isn't as much going on screen, if you compare it to KZ2, MGS4, GTA4. If the rumors are true that MGS4 cost $50M to develop, I am thinking the development cost for GT5 is about $40 - 45M. 

Taking revenue of $33.5M and development cost of $40-45M, I would say GT5:P profit has paid for between 60% (conservative) and 75% (optimistic) of GT5 development costs, at the moment. By the time GT5 releases, I would think the development costs of GT5 will just about be covered by the profit of GT5:P. 

What do you think?

the truth is that GT5:p did help alot,,,,I am just hoping for a damage model in the full game.

I think it paid about atleast half of the GT:5 production costs.

I think close to $100 million like GT4.

Considering all the cars and tracks they put in GT5, i think around $40 mil sounds correct, perhaps a bit less. If prologue continues to sell or even hits 3 million, they very well cover the development costs before the actual full game comes out.

Remember that they will get a bigger cut from the downloaded copies than the retail ones.

50-75$ million...If it was more we probably would have a lot of threads 'GT5 the most expensive game ever to develop* Or something like that;

no i dont think it covered its developement cost,but it helped alot

Probably about half. GT Mobile is sort of lumped in there, and its all about funding the entire Polyphony company. They also have other back sales.

Licensing all of the cars, and doing things like recording accurate sounds for the cars won't be an easy (or cheap) thing to do.

GT5 is likely to have an overall development & marketing budget approaching 80m-100m. So even if GT Prologue covered 25% of this - its a good return.

(since its Sony published, they are likely to make a few extra $ from each software unit sold as well)

I remember reading that a couple car companies give Polyphony free licenses to use their cars because the game is so popular.  I'm not sure what the situation is now, especially if Polyphony wants to incorporate car damage, but considering how big and popular the GT series is, I'm sure more than a few companies would jump at the chance to have their cars in GT5.