What difference does it make if Jesus lives forever? Actually, it makes a huge difference. As Jesus is the one who died for our sins and rose again victorious, it makes a great deal of difference that He is still living. See what it says in Hebrews chapter 7.
but Jesus, on the other hand, because He continues forever, holds His priesthood permanently. Therefore He is able also to save forever those who draw near to God through Him, since He always lives to make intercession for them.
Hebrews 7:24-25 NASB
Because Jesus is the one who died on our behalf and who intercedes for us, the fact the he still lives to continue to do that is crucial. He has a permanent priesthood because He will never die or cease to do that which He has already done. We can trust in Jesus because He always lives to stand in the gap between us with our sin and a Holy God.