Misleading headline. Based on these numbers said witches only outnumber a single denomination of Presbyterians (the very liberal unChristian one at that) and one that has been losing members in masses for years and currently overstates it's membership dramatically.
All other Presbyterian denominations, combined, are much smaller than the PCUSA.
You can’t know how many members PCUSA has, certainly, only a fraction of their claimed membership attends church on Sunday, which probably indicative of their true membership.