In 1 Nephi 10:8, Lehi’s language parallels that of the synoptic Gospels (Matthew 3:3, Mark 1:3, and Luke 3:4), which derives from the Septuagint version of Isaiah 40:3. As a result, the printed editions have consistently had the correct straight rather than the strait of the manuscripts. For other passages, the issue regarding strait versus straight is often more complex. For a complete discussion, see under 1 Nephi 8:20; for a complete listing of the textual variation, see strait in volume 3.
Summary: The phraseology in 1 Nephi 10:8 of “make his paths straight” follows the language of the synoptic Gospels in describing John the Baptist’s mission; thus straight is the correct reading.