Welcome
None of the info in EF's upgrades section is really relevant to whether a bid upgrade will be successful. AC accepts (or doesn't) bid upgrades at T-48 hours before the flight (usually, although I think a few have reported occasional discrepancies). Their willingness to accept upgrades at that point depends on how many seats they've sold in the cabin by then. What EF is showing you there is what's
currently available in the R fare bucket (for eUpgrades), the I fare bucket (partner reward tickets) and the Z fare bucket (which no longer has anything to do with upgrades - and never had anything to do with upgrades on a TATL flight - and should be removed from their site). Knowing that there are 6 seats for sale in Z is better than knowing there are 0 seats in Z, but there could be 6 unsold seats in the cabin or 30.
If you were to check the regular availability and see the whole spread of what AC is selling on that flight (currently J6 C6 D6 Z6 P0 R0), it might give you a slightly better idea, but it's still of limited predictive value, even only 5 days out. J6 is better than J0, obviously, but J9 would be better. Of course, even if it were J9, the true availability could be 9 or it could be 30.
Ultimately, there's going to be
some correlation between J space and your odds of winning the bid upgrade, but your result is dependent on how many seats AC sells between now and clearing bid ups, how many seats it thinks it can sell after T-48 (they don't clear bid ups in to every available seat), how many people are waitlisted for eUps that AC might want to upgrade ahead of bid ups, how many people have bid more than you on the eUp, and a few other factors. So the correlation is going to be somewhat weak.