Based on customer surveys, you should be confident no matter how large or small your coffee shop is. This isn't really a factor for customers even though many have the impression that large coffee shops have more to offer. A customer may try a new large coffee shop but then go back to the smaller one they have gone to for a very long time.
Just because you have a large coffee shop doesn't mean people will come in and fill it up either. In fact, going this route can result in your business not doing very well from the start. You have to be able to attract a large customer base to keep the doors open on a big coffee shop location.
Customers have other criteria that they are concerned with than the size of the location. People even go to drive up ones if they offer the right elements. They include fast service that is friendly, delicious coffee products, good prices, and a nice atmosphere. All of these things can be found at a small independent coffee shop or a large chain business.
The atmosphere is very important though. Many people find it is more personal at a smaller sized coffee shop. They are able to get to know the people behind the counter. They are also warmly greeted by name each time they walk in the door. With a large coffee shop this may not be possible. There are simply too many people and too many different employees for it to work.
Many of the large coffee shops are able to succeed due to being a chain. They are already known in the eyes of consumers as a great place to get coffee. There is also a stigma that comes with visiting such a location for some people. They still have to work to meet the needs of the customers though or they will lose business rapidly.
People don't want to feel crowded, so that can be an issue to address with a small coffee shop. If people want to sit down and enjoy their drinks, it may not be possible due to the small number of tables available. You may be able to find a way to reorganize them though to give more room. Consider more tables for one or two people instead of larger ones as well.
You don't need to have a large coffee shop to be successful in this line of businesses. You do have to strive to offer all of your customers a great experience though. Work hard to offer them the best tasting products out there for a fair price. You also need to concentrate on the areas of customer service and the overall atmosphere of the place.
There are small coffee shops that continue to grow in the number of customers. They may decide to expand in order to better serve them. This is an individual business decision that could prove to be a good move. However, if your business is already struggling, making the coffee shop bigger isn't going to solve your problems.