I never majored in marketing by I know a few things about it from working for a corporation.
A corporation agrees to finance an event, organization, or person. The amount of money involved and the terms behind the sponsorship vary from deal to deal, but in most cases the corporation (i.e. 5-Hour Energy or Just for Men) receives tons of free, long-term advertising while the sponsored group (i.e. TNA or WWE) receives a great deal of financing.
The corporation itself benefits from increased brand recognition and the free advertising that comes with the sponsorship. Do you recall all those Slim Jim commercials that were on WWE for the longest time? TNA and the WWE benefis from the capital that is raised and is able to do things that would be impossible without such funding such as getting Floyd Mayweather or J-Woww for the $20 million or $10,000 they cost. TNA especially since a lot of their tickets are given away for free. Getting people like that can cost up to a third to half of of their PPV cash or whatever cash they got from a live event.
The fans benefits from the fact that sponsorships make tickets affordable and low enough for fans to purchase.
Look at NASCAR as an example, logos are everywhere on these cars. This increases the number of people who see whatever brand is on there. Now if the car starts winning and continues to do so the brand becomes synonymous with winning. More people start buying that product and the corporation pays more money to the organization to keep them advertising for them.
Many of the new stadiums around the country exist solely because of funds raised by corporate sponsorship of those stadiums. Even video games like Fight Night (Burger King), Blur (T-Mobile), and Mass Effect (Dr. Pepper) have sponsors which gave them money to produce to high quality games. Movies like Batman (Visa) and Demolition Man, (Taco Bell) have sponsors which help pay for productions quality and cast and crew.
Take all that and apply it to wrestling. These sponsorships help pay for talent, travel expenses, labor, production, writers, and more. Ticket sales are very important but they are only a piece of the whole pie. Not nearly enough to keep the company afloat. It's merchandising and corporate sponsorships that bring in the big bucks.
The more successful the company is, the more viewers watch it. The more viewers watch, the more different corporations vie for advertisement time on the program. The more they vie for time, the more money they offer. This is why it costs millions of dollars for 30 seconds of ad time during the Superbowl. Everyone is watching it.
My knowledge of all this is very basic and probably comes off as such, but in a nutshell that's how it works.