No, a person is not eternally tortured if he commits suicide. When a person dies, he goes into the grave. The Bible explains that the grave is a condition of unconsciousness.

Eccl. 9:5, 10, "For the living know that they shall die; but the dead know not any thing…there is no work, nor device, nor knowledge, nor wisdom, in the grave (Hebrew word sheol, Strong's word 7592)…" This same Hebrew word sheol is translated as grave, hell, and pit in the King James Bible. It confuses the issue, because all people, good and bad, go to sheol in the Old Testament. In the New Testament, when Lazarus died, Jesus said, "Our friend Lazarus sleepeth,…" What did Jesus mean by sleeping? A few verses later Jesus explained, "Lazarus is dead." John 11:11, 14. Therefore, both Old and New Testaments agree that the state of death is unconsciousness.

I Sam. 31:4, 5 records two suicides, "Then said Saul to his armor-bearer, 'Draw you sword, and thrust me through with it, lest these uncircumcised come and thrust me through, and mistreat me.' But his armor-bearer would not, for he feared greatly. Therefore Saul took his own sword and fell upon it. And when his armor-bearer saw that Saul was dead, he also fell upon his sword and died with him." Neither man stated he was worried about going to eternal torment. In fact, even if King Saul had been temporarily captured and abused, if he had feared torment after death, why would he commit suicide? No. King Saul and his armor-bearer feared torture in the present. They chose suicide to escape torture.