Economic benefits of ecotourism anyone

You have gotten two good answers, but I'd like to add a reference to a very indirect and often overlooked (by everyone except the ecologists) economic benefit.

In a less developed country, people are generally economically deprived and simply cannot afford to protect their own environment for future generations. Eco-tourism puts money into the economy in a way that convinces the local residents that protecting their own environment is not just a drain on resources, but can contribute to economic advance. The indirect benefit of that is that the environment will be saved for future generations, and that will have a substantial long-term benefit for those descendants.

There are direct and indirect. The more obvious are the jobs and the overflow expenditures that tourists make in related business (think of the flights, hotels, car rentals, restaurants that also benefit from increased ecotourism activities). The indirect benefits are the ecosystem services that ecotourism protects. Many parks and protected areas provide clean water, oxygen, wildlife, and many other natural resources that are typically taken for granted in economic calculations. These areas also prevent erosion and siltation of rivers, and absorb considerable amounts of carbon through their forests. I will put a link to a great example of one such project in Mozambique.

Economic benefits, including entry fees, licences and concessions, often generate substantial funds to support conservation and management of natural environments.
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I hope this is helpful.