Giving money to Haiti doesn’t seem like enough? Katmanda have another suggestion: grant Haitians Temporary Protected Status.
TPS is a form of temporary humanitarian immigration relief given to nationals of countries that have suffered severe disasters, natural or man-made. (For example, El Salvador got TPS was after the country was hit by a terrible earthquake in 2001, Honduras after Hurricane Mitch in 1999, and Burundi, Liberia, Sudan, and Somalia were designated because of ongoing armed conflicts.)
Once a country has been given TPS, its nationals who are in the United States can apply for work authorization (a very useful thing to have if, say, one needs to send money home to family members in need of medical care or a house that has not been reduced to rubble), can’t be deported or put into immigration detention (also quite handy if you’re trying to work and send money home), and can apply for travel authorization, which allows them to visit their home country and return to the US, even if they wouldn’t otherwise have a visa that would allow them back into the country (incredibly important if you have loved ones who have been badly hurt and need to visit them, or if you need to go home to attend funerals).
To support TPS, contact the White House here. You’ll need to select “I have a policy comment”, and “Immigration” from the drop-down menu.
Alternatively, as Michael Clemens suggests, simply let their people come.