What is the amount of entitlement that should be obtained from a person who took money for investment, then absconded, which led to filing a lawsuit and incurring expenses for pursuing the case?

If the person mentioned is a swindler, then your right is limited to the amount he took from you and what you spent in recovering it and prosecuting him, because the cost of the usurped item falls on the usurper, and "the expense of restitution is obligatory upon the usurper." As for the expected profits from this amount, had you invested it, you have no right to them, due to the uncertainty of their occurrence, and because investment is subject to profit and loss.