SFO-TPE is not a difficult route in general, but 4/21 is a Sunday which is notably difficult to clear TPAC. 4/26 is a Friday, which is a little better, but dicier than midweek.

The inventory figures don't provide information sufficient to provide an informed estimate. You really need the booking numbers to make any kind of informed estimated. It also helps to watch the flight for a while to see if PN has opened, as that will take GS off the waitlist, increasing odds 1K clears.