Acid reflux CAN cause bad breath.
More Info: Many studies have refuted the fact that acid reflux, also called gastroesophageal reflux disease or GERD, causes bad breath (halitosis). However, a 2008 study published in the Journal of General Internal Medicine concluded that there is clear evidence that there is a strong association between acid reflux and bad breath. 
What Causes Bad Breath?
Many factors contribute to the incidence of bad breath including poor oral hygiene, food consumption, and health problems. The most common contributors to halitosis are periodontal diseases and tongue coating.  Foods that you ingest are absorbed into your bloodstream, carried to your lungs, and given off in the air you expel. Smoking, dentures, and dry mouth can also lead to halitosis. Several medical conditions have been indicated as increasing the incidence of bad breath including acid reflux, chronic sinus infections, pneumonia, bronchitis, diabetes, and liver and kidney problems. 
How Does Acid Reflux Cause Bad Breath?
Acid reflux is so named because the condition causes the contents of the stomach and intestinal gas to reflux back into the esophagus. This alone could produce a foul odor. These acids can also cause irritation to the walls of the nasopharynx, the uppermost part of the throat below the nasal cavity. This, in turn, can cause postnasal drip, which is a common cause of halitosis. The acids can also injure the tissue of the esophagus, which can produce a foul odor. 
Acid reflux can also cause dental problems, which is a common cause of halitosis. 
How to Prevent Bad Breath from Acid Reflux
Control Acid Reflux. If your bad breath is caused by acid reflux, rather than any of the other common contributors, treating your acid reflux may help to get rid of bad breath. Medications, such as proton pump inhibitors, can help to suppress the stomach acids that may be the cause of halitosis. 
Baking Soda Rinse. Chronic acid reflux can cause erosion of tooth enamel and other dental problems. Rinsing with a solution of water and baking soda four times a day will help to neutralize the acid before it erodes the tooth enamel. One teaspoon of baking soda mixed in one cup of water should do the trick. 
Brush Your Tongue. Bad breath can be caused by bacteria on your tongue. Brushing your tongue should be part of your tooth brushing routine. Bacteria tend to migrate to the back of the throat so be sure to brush as far back as you can without gagging.
Gargle with Peroxide. WebMD suggests gargling with peroxide to ward of halitosis. The oxygen in the peroxide can effectively kill bacteria. Gargle as you would any mouthwash and be sure to spit it out when you done rinsing. 
 Gen Intern Med, Franziska Struch
Self-reported Halitosis and Gastro-esophageal Reflux Disease in the General Population
2008. Volume: 23. No: 3. Pages: 260-266
 Ned Tijdschr Tandheelkd, Vandekerckhove, B
The role of periodontal disease in bad breath
2002. Volume: 109. No: 11. Pages: 430-433
Bad Breath Causes, Treatments, and Prevention
 Journal of General Dentistry, Lazarchik, DA
Dental Erosion and Acid Reflux Disease: an Overview
2009. Volume: 57. No: 2. Pages: 151-156
 National Institute of Dental and Craniofacial Research
Practical Oral Care for People with Disabilities
15 Tips to Freshen Your Breath