As of June 30 2015, Shovel Knight has sold about 700,000 "copies". The game generally costs $15 USD. Using the power of math, Shovel Knight has made ~10,500,000 USD. The game was developed with around $311,000. So its safe to say Shovel Knight has been very profitable.
But that's just one game. Most indie games have different budgets. The budget, quality, and sales all correlate usually.
bet: lost