If you constantly watch porn will God give you up to vile affections? I'm constantly worried that when I watch porn and fail that God will give me up to vile affections and make me gay and stuff for punishment. Is this true?
If you ignore any sinful thing that you are doing and treat it as acceptable, God isn't going to hold you back from sin. "and with all unrighteous deception among those who perish, because they did not receive the love of the truth, that they might be saved. And for this reason God will send them strong delusion, that they should believe the lie, that they all may be condemned who did not believe the truth but had pleasure in unrighteousness" (II Thessalonians 2:10-12).
You should not be accepting the fact that you are watching porn. God calls chasing after lust sinful. "For this is the will of God, your sanctification: that you should abstain from sexual immorality; that each of you should know how to possess his own vessel in sanctification and honor, not in passion of lust, like the Gentiles who do not know God" (I Thessalonians 4:3-5).
You have no need for pornography in your life. Constantly thinking about sin and lusting after it in your mind makes you vulnerable to actually sinning when the opportunity arises. "For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, thefts, covetousness, wickedness, deceit, lewdness, an evil eye, blasphemy, pride, foolishness. All these evil things come from within and defile a man" (Mark 7:21-23).
So does this mean if I do not stop watching porn fast enough God will make me gay because He's giviing me up to vile affections?
God doesn't make anyone sin. "Let no one say when he is tempted, "I am tempted by God"; for God cannot be tempted by evil, nor does He Himself tempt anyone. But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death. Do not be deceived, my beloved brethren" (James 1:13-16). But then, if you insist on filling your mind with thoughts of homosexuality and start justifying it in your head, God isn't going to hold you back either. That is what is meant by "For this reason God gave them up to vile passions" (Romans 1:26). God tries to keep people from sin, but if they insist on it, then eventually God will stop holding them back.
Therefore, God isn't making you a homosexual. You are chasing after homosexuality by filling your mind with pornography. So far, God has kept Satan from offering you actual sex, but if you keep insisting on going this direction, God will let Satan tempt you with having sex with a guy.
You can't play with fire and not expect to eventually get burned.