Here's the huge list of Game of Thrones episodes and air dates.
Season 1 (2011)
1 - April 17, 2011 - "Winter Is Coming"
2 - April 24, 2011 - "The Kingsroad"
3 - May 1, 2011 - "Lord Snow"
4 - May 8, 2011 - "Cripples, Bastards, and Broken Things"
5 - May 15, 2011 - "The Wolf and the Lion"
6 - May 22, 2011 - "A Golden Crown"
7 - May 29, 2011 - "You Win or You Die"
8 - June 5, 2011 - "The Pointy End"
9 - June 12, 2011 - "Baelor"
10 - June 19, 2011 - "Fire and Blood"
Season 2 (2012)
11 - April 1, 2012 - "The North Remembers"
12 - April 8, 2012 - "The Night Lands"
13 - April 15, 2012 - "What Is Dead May Never Die"
14 - April 22, 2012 - "Garden of Bones"
15 - April 29, 2012 - "The Ghost of Harrenhal"
16 - May 6, 2012 - "The Old Gods and the New"
17 - May 13, 2012 - "A Man Without Honor"
18 - May 20, 2012 - "The Prince of Winterfell"
19 - May 27, 2012 - "Blackwater"
20 - June 3, 2012 - "Valar Morghulis"
Season 3 (2013)
21 - March 31, 2013 - "Valar Dohaeris"
22 - April 7, 2013 - "Dark Wings, Dark Words"
23 - April 14, 2013 - "Walk of Punishment"
24 - April 21, 2013 - "And Now His Watch Is Ended"
25 - April 28, 2013 - "Kissed by Fire"
26 - May 5, 2013 - "The Climb"
27 - May 12, 2013 - "The Bear and the Maiden Fair"
28 - May 19, 2013 - "Second Sons"
29 - June 2, 2013 - "The Rains of Castamere"
30 - June 9, 2013 - "Mhysa"
Season 4 (2014)
31 - April 6, 2014 - "Two Swords"
32 - April 13, 2014 - "The Lion and the Rose"
33 - April 20, 2014 - "Breaker of Chains"
34 - April 27, 2014 - "Oathkeeper"
35 - May 4, 2014 - "First of His Name"
36 - May 11, 2014 - "The Laws of Gods and Men"
37 - May 18, 2014 - "Mockingbird"
38 - June 1, 2014 - "The Mountain and the Viper"
39 - June 8, 2014 - "The Watchers on the Wall"
40 - June 15, 2014 - "The Children"
Season 5 (2015)
41 - April 12, 2015 - "The Wars to Come"
42 - April 19, 2015 - "The House of Black and White"
43 - April 26, 2015 - "High Sparrow"
44 - May 3, 2015 - "Sons of the Harpy"
45 - May 10, 2015 - "Kill the Boy"
46 - May 17, 2015 - "Unbowed, Unbent, Unbroken"
47 - May 24, 2015 - "The Gift"
48 - May 31, 2015 - "Hardhome"
49 - June 7, 2015 - "The Dance of Dragons"
50 - June 14, 2015 - "Mother's Mercy"
Season 6 (2016)
51 - April 24, 2016 - "The Red Woman"
52 - May 1, 2016 - "Home"
53 - May 8, 2016 - "Oathbreaker"
54 - May 15, 2016 - "Book of the Stranger"
55 - May 22, 2016 - "The Door"
56 - May 29, 2016 - "Blood of My Blood"
57 - June 5, 2016 - "The Broken Man"
58 - June 12, 2016 - "No One"
59 - June 19, 2016 - "Battle of the Bastards"
60 - June 26, 2016 - "The Winds of Winter"
Season 7
61 - July 16, 2017 - TBA
62 - July 23, 2017 - TBA
63 - July 30, 2017 - TBA
64 - August 6, 2017 - TBA
65 - August 13, 2017 - TBA
66 - August 20, 2017 - TBA
67 - August 27, 2017 - TBA
As you can see, the air dates have always been pretty consistent.