Didn't the CBO say that 500,000 jobs would be lost?

Sort of, but not really. In February 2014, the Congressional Budget Office (CBO) issued a report on possible effects of increasing the minimum wage to $10.10 per hour. This is the full quote from the report's summary...

Once fully implemented in the second half of 2016, the $10.10 option would reduce total employment by about 500,000 workers, or 0.3 percent, CBO projects. As with any such estimates, however, the actual losses could be smaller or larger; in CBO's assessment, there is about a two-thirds chance that the effect would be in the range between a very slight reduction in employment and a reduction in employment of 1.0 million workers.

The statement explains that the estimate simply is the middle ground between the equal possibilities of no job loss and the loss of 1 million jobs.

However, as we explain in the summary section for this issue, studies performed since 2000 have consistently shown negligible loss of employment correlating to minimum-wage increases.

Lastly, even if the higher number turns out to be accurate...

For a more in-depth look at this issue, read the Center for American Progress analysis.