Is it common for engineers to earn minimum wage?
Apparently, it's pretty rare for skilled workers to even earn 100% of minimum wage. The median income for Venezuela is approximately 60% below minimum wage. In black market exchange rates, that equates to approximately $2 USD per month.
The maximum surveyed income, according to SalaryExplorer, is 72,000 bolivars per month, which amounts to approximately 10x minimum wage, or around $100 a month.
Given the median though, one assumes that is an extreme outlier.
"Working with some guys there" is not as reliable a source as a guy who actually lives and works in the country. You shouldn't have called him a lier.