“First they ignore you, then they laugh at you, then they fight you, then you win” has been attributed to Mohandas Karamchand Gandhi (1869-1948), but there is no evidence that he said it. The Gandhi attribution dates to at least 1982.
 
A similar statement was given by Nicholas Klein at a convention of the Amalgamated Clothing Workers of America in 1918 (the Wikipedia date of “1914” appears incorrect):
   
“And my friends, in this story you have the history of this entire movement. First they ignore you. Then they ridicule you. And then they attack you and want to burn you. And then they build monuments to you.”
 
 
Wikiquote: Mohandas Karamchand Gandhi
Mohandas Karamchand Gandhi (2 October 1869 – 30 January 1948), commonly known as Mahatma Gandhi (Sanskrit: महात्मा mahātmā — “Great Soul”) and in India as Bapu (Gujarati: બાપુ bāpu—“Father”), was an advocate and pioneer of nonviolent social protest in the form he called Satyagraha. He led the struggle for India’s independence from British colonial rule.
(...)
Disputed
. “First they ignore you, then they laugh at you, then they fight you, then you win.”
.. Describing the stages of a winning strategy of nonviolent activism. A close variant of the quotation first appears in a 1914 US trade union address:
“And, my friends, in this story you have a history of this entire movement. First they ignore you. Then they ridicule you. And then they attack you and want to burn you. And then they build monuments to you. And that, is what is going to happen to the Amalgamated Clothing Workers of America.”
General Executive Board Report and Proceedings, Biennial Convention, Amalgamated Clothing Workers of America (1914)
   
Google Books
Proceedings of the third biennial convention of the Amalgamated Clothing Workers of America, held in Baltimore, Maryland, May 13 to 18, 1919.
(1918 appears to be the correct date—ed.)
Pg. 47:
Fourth Session.
Baltimore, Md., Wednesday, May 18, 1918
Pg. 53 (Address of Nicholas Klein):
And my friends, in this story you have the history of this entire movement. First they ignore you. Then they ridicule you. And then they attack you and want to burn you. And then they build monuments to you.
 
And that is what is going to happen to the Amalgamated Clothing Workers of America.
 
8 October 1968, Women’s Wear Daily, “Revolting” by Patricia McColl, pg. 4:
“Cocteau expressed it best. ‘First, they ignore you. Then, they abuse you. Then, they heap you with honors. Or make you into a statue. Stone. Dead.’”
 
Google Books
WIN: Peace and freedom through non-violent action
Committee for Nonviolent Action, New York Workshop in Nonviolence, War Resisters League
Brooklyn, NY: Workshop in Nonviolence Institute
Volume 18
1982
Pg. 9:
Gandhi once observed that every movement goes through four stages: First they ignore you; then they abuse you; then they crack down on you and then you win.
     
Google News Archive
27 January 1987, Eugene (OR) Register-Guard, letters, pg. 8A, col. 3:
Gandhi, speaking of the normal life cycle of non-violence campaigns, said, “First they Ignore you, then they laugh at you, then they crack down. Then you win.”
   
January 1992, Music Trades, “It can all be yours ... if you believe. (keys to business success)” by Bob Popyk:
“First they ignore you, then they ridicule you, then they copy you, then they say they invented it.” Mr. Redding could be ahead of his time.
     
Green Left
John Pilger: We can win a peaceful world!
17 November 1993
(...)
Remember the words of Mahatma Gandhi: “First, they ignore you. Then they laugh at you. Then they fight you. Then you win.”
   
Google Books
The Good Fight:
A Laura DiPalma mystery
By Lia Matera
New York, NY: Ballantine Books
1994
Pg. 59:
Remember what Gandhi said—“First they ignore you, then they laugh, then they crack down, then you win.”
 
19 November 2000, Syracuse (NY) Herald-American, “Local Green leader says wealthy run U.S., city” by Sean Kirst, pg. A12, col. 5:
“One of the quotes going around among the Greens to keep our spirits up is a quote from Gandhi that goes something like this: ‘First they ignore you. Then they laugh at you. Then they attack you. And then you win.’”
   
Google Books
Tangled Up in the Past
By Bob Ferchat and Tony Carlson
Toronto: I.magin.ation, Inc.
2002
Pg. 1173:
First they ignore you, then they laugh at you, then they fight you, then you win.
Mahatma Gandi