Here is a history of how to spell קבלה. Notice the changes of the spelling and recent vintage of our current spelling of kabbalah. Most spell checks still use cabala. It seems that the publication of the Encyclopedia Judaica in 1971-2 changed the spelling to kabbalah. What other words did the EJ change? Qabbalah has still not caught on and cabbala has declined. Also notice the interest in the esotericism of the cabbala as a subject between 1810-1840. Click on the chart to enlarge.
Thanks to Yosef Rosen and Satya of Berkeley for the above chart.