There is no question whatsoever that many illegals voted, and the vast majority voted for Clinton. One needs look no further than the concerted efforts by democrats to oppose even the most rudimentary voter ID laws to know that the democrats know they benefit immensely from fraudulent voters. If that were not the case, why in the world would they be so adamantly behind preventing voting requirements that any sane person would support?
This is very vague... What voting requirements are you talking about? Some of them disproportionately impact Democratic voters. For instance, Republicans generally oppose same day registration.. that's fine for them because most of their voters are old and/or rural voters that don't tend to move a lot and just register in one county for a long time. On the other hand, democrats tend to be younger, more urban and transient and forget to register to vote until right before major elections. Obviously making it more difficult to register disproportionately impacts Democrats. I believe that is the main reason Democrats oppose stricter voter laws, not because they want to cart busloads of people from Mexico to vote illegally.
Additionally, a lot of the states where this issue has popped up, e.g., North Carolina, don't have massive amounts of illegal immigrants. The fight is largely about how Republicans cut back early voting locations and hours.
Democrats have teams of lawyers fighting the simple requirement to show an ID to vote. That is the one that has allowed massive voting by illegals.