Olive trees and light bearers...
(Candlestick is misleading)
Refers to the tabernacle, and the seven branched lamp-stand. It was fed by pure olive oil. Oil is a frequent idiom for the Holy Spirit.
These two, idiomatically, are two lamp stands/light bearers, tapped directly into the source. The Spirit gives them an in-exhaustible supply of His oil, for as long as it suits God's plan.
At Pentecost, (or John 20, when Christ breathed on them) the Spirit came upon the Church. After the rapture, the Spirit (restrainer of 2 Thes 2:7) no longer indwells "those that dwell on the earth". The Spirit, in the OT pattern, becomes conditional and temporary (David: "take not thy Holy Spirit from me..."). We, today, can not validly pray that prayer. These two witnesses, in contrast to the earth-dwellers, DO have a permanent in dwelling of the HS.