Luke 6:23

“Rejoice in that day, and leap for joy,

For behold, your reward is great in heaven,

For in the same manner did their fathers to the prophets.”

Yes, if they are persecuted for His sake they can rejoice and jump for joy, for they will receive great reward in Heaven, for that is how God's prophets were treated when they too came on earth (including John the Baptiser). By their response as described above they will be aligning themselves with the true prophets, who also sought only to please God, and they will therefore enjoy a prophet's reward.

The reference to the prophets may have in mind:

1) That as the prophets were persecuted they too must expect to be persecuted (Luke 11:47; Luke 11:49; Luke 13:34; Matthew 23:29; Matthew 23:34).

2) That as the prophets have gone to their reward (Luke 13:28), so will they too go to their reward.

3) The fact that they will be persecuted is positive proof that they are equal with the prophets and will therefore enjoy both what they suffered and what they will receive (compare 1 Peter 4:12).

The mention of the reward is not as a kind of bribe. Those whose eyes were only on a reward would not be welcome, or genuine. The point was that having chosen to walk in God's way, it was something that they could look forward to. It was an incentive while they were in the way.

Note the reference to  their  fathers. Jesus has already divided Israel into two parts, those who are for Him and those who are against Him, the old Israel and the new.