Does my salvation depend on how much faith I have?
No, salvation does not depend on the amount of faith you have. It depends on the faithfulness of Christ, the object of faith. He has done everything necessary, and the blood of Christ is faithful. His love and faithfulness keep us, not the strength or quantity of our own believing.
Les teaches that salvation is not measured by the strength or amount of our faith, but by the faithfulness of the One in whom we trust. He uses the illustration of a chair: you sit without inspecting it, trusting the chair to hold you, and the chair must be faithful. Likewise, Christ has claimed to have done everything necessary, and faith rests in that. Les says that when we reach the eternal abode, God will not say it was not what it seemed; He will declare the blood of Christ is faithful. Because Christ is faithful, we can trust Him; Paul is driving at salvation through His faithfulness to keep us. Les also recounts his grandson asking if he loves God enough or has enough faith. The answer is that it is not how much we love Him, but how much He has loved us.