A major cause of Candida infections is that you have a weakened immune system. The Candida lives in your body, and often times it forms over growth when you take antibiotics, or are sick. Either way, the Candida comes to people who have weak immune systems, so one can assume that having a strong immune system would be a good way of combating Candida. In that sense Candida is not different than any cold or flu, as if you have a stronger immune system, you will deal with it far better.
Echinacea is not specifically formulated to fight Candida, but instead strengthens your immune system. According to the NIH it appears that the evidence that Echinacea strengthens your immune system is very plausible http://www.ncbi.nlm.nih.gov/pubmed/15035888.
With a strengthened immune system, your body will be able to fight Candida far better than if your immune system was weaker. If you actually care about getting rid of your Candida, the next step you will take is ensuring you are on an ideal diet. By an ideal diet, I mean getting rid of grains, sugars, and eating foods that will ensure you get rid of Candida.