The Survival objective requires you to “Win the fight with 9 or less HP remaining”. The progress bar seems to display the percentage of your HP remaining.
I just finished Origins - Chapter One Part 2 - Battle 12, and when my planeswalker was at 9 HP (out of 44), the meter for the objective read 20/9. I had good control over the board at that point, so I let my HP drop to 4 before finishing off the Hangarback Walker. This completed the objective. I haven’t yet tested whether you can complete the objective if you win with 9 HP remaining and that’s more than 9% of your total HP.
It seems like either the objective description or the progress meter needs to be tweaked.