What needs to be taken into consideration regarding what Jesus said, is that it was all said before the Cross. After the resurrection, Jesus bridged the separation. That's why there's so many illustrations of the Cross acting as a bridge across a gulf / chasm. Jesus bridged the separation.
Good point. The parable of the rich man and Lazarus appears on the surface to be evidence for ECT because of verse 26: “between you (the rich man) and us (Abraham, Lazarus and everyone else in heaven) a great chasm has been fixed, so that those who might want to pass from here to you cannot do so, and no one can cross from there (Hades) to us.”
But, as you say, this is talking about the time before Christ’s death and resurrection and it's true that at that point, those in Hades were not savable. But that's the entire point of Christ’s sacrifice! He rescued everyone trapped in, or on the path to, Hades and allowed them to enter into heaven. This parable is not describing ECT but is illustrating why Christ’s upcoming death is necessary in the first place.
Saying that “no one can cross from” Hades to Heaven means that no one can
ever cross over also contradicts other parts of the NT. Peter says that Christ brought the Gospel to those who were dead in Hades: “He (Christ) was put to death in the flesh, but made alive in the spirit, in which also he went and made a proclamation to the spirits in prison, who in former times did not obey, when God waited patiently in the days of Noah, during the building of the ark, in which a few, that is, eight persons, were saved through water” (1 Peter.3:18-20). And later, in 1 Peter 4:6: “For this is the reason the gospel was proclaimed even to the dead, so that, though they had been judged in the flesh as everyone is judged, they might live in the spirit as God does.”
Why is the Gospel being preached to those in Hades if their fate is ECT?