要看语境啊!从语法上看,两个都可以：
Though he thought he could escape from it by running away,he was wrong.
-----尽管他觉得他可以逃跑,但是他错了.
If he thought he could escape from it by running away,he was wrong.
---- 如果他觉得他可以逃跑,那么他就错了.