Indian startups like OLA, Zomato, Flipkart & MakeMyTrip are running at a loss despite some of them in operation for more than 5 years, yet they get huge funding. Why? What is the long term strategy in terms of revenue? How does this benefit the investors & founders?

Why they get huge Funding?

They get huge funding, for one and only reason.

You invest more, to get more returns.

Go back in time in early 2000's , when name of google just got out, and let's say you invested 2 million in them... then, you would have been a billionaire by now.  Just like Warren Buffet did

Why The Coca-Cola Company is One of the Biggest Warren Buffett Stocks --  The Motley Fool

So Investors hope that the company they are investing in will become a giant one day and they will be richer by almost 10x their investment. This gamble keeps them in the game.

But again they aren't stupid. They ask like 1000 questions before investing and it may seem like flipkart, ola don't have a plan and are just burning cash, they will actually have a plan to control it and make themselves profitable in a time bound manner to get funding once again. Because funding is always metric based. You perform you get more funding, you don't perform, nobody will give you money.

Ques 2 : What is their Long term strategy ?

1. Well it could be that they want to be the market leader in their segment, thus creating a monopoly. So that if you want to buy online, you have only 1 choice or at max 2.
2. Make you habitual of the product and later increase price to compensate for their losses.
3. Monetizing their existing infrastructure. Flipkart to throw open its logistics arm 'eKart' to deliver packages of competitors
4. R & D to develop new products, which will also fetch money.
5. Acquiring business which will become profitable hence providing them with sustenance option.

and many many more.

How does this benefit Investors and founders? 

Investors have one and only goal. To get returns from their investment.Well not all are only thinking about money some care about the product too, but majority does. So in short  they want returns. Founders are always trying to solve new problems, all they want to do is solve problem and for that they need money, hence they sell their stake, to generate more money to solve problems(Some do it for the money too, not all are saints, getting acquired is the best way to do that and that to in a all cash deal)

I hope you I answered all your queries, for further reading there are beautiful answers here . Do give them a read too.