1.  Marriage Record:

2.  1840

3.  1850 Census Index/Images (online at Ancestry.com; Image #10 of 33):  Perry [now West Perry] Twp., Union [now Snyder] Co., PA, p. 102B, 64/64, enumerated 15 Nov 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

John Hass	36	M		Farmer		Penna
Maria Haas	28	F				"
Elithebeth Haas	8	F				"
Daniel Haas	4	M				"
Augustes Haas	8/12	M				"
Miah? Neiser	15	M				"

Listed next to John's father, Capt. Valentine HAAS. 

4.  1860

5.  1870 Census Index/Images (online at Genealogy.com, Image #4 of 16):  Mt. Pleasant Mills P.O., West Perry Twp., Snyder Co., PA, Roll 1451 (Book 1), p. 205B, PN 4, 31/31, enumerated 8 Aug 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤

Haas John	56	M	W	Farmer	4000	1000	Pa
____ Mary	48	F	W	Keeping House			Pa
____ John	14	M	W				Pa
____ Rebecca	68	F	W				Pa

Rebecca HAAS is our subject's sister. 

6a.  LDS.  Family Search: Census Records: 1880 United States (online at FamilySearch.org):

Census Place: West Perry, Snyder, Pennsylvania
Source: FHL Film #1255194; NARA Film #T9-1194; Pg 154B
	Relation	Sex	Marr	Race	Age	Birthplace	Occupation	Fa	Mo
George H. SHAFER	Self	M	M	W	41	PA	Farmer	PA	PA
Elizabeth SHAFER	Wife	F	M	W	38	PA	Keeping House	PA	PA
[George & Elizabeth's children]
John HAAS	Other	M	S	W	66	PA	Farmer	PA	PA
Mariah HAAS	Other	M	S	W	58	PA	Keeping House	PA	PA

Elizabeth SHAFER is our subjects' daughter. 

6b.  1880 Census Images (online at Ancestry.com, Image #42 of 44; online at Genealogy.com, Image #14 of 16 — the images at both sites are so poor, we'll have to trust the LDS extraction):  West Perry Twp., Snyder Co., PA, Roll 1194 (Book 2), p. 154B, PN 14/40, SD 7, ED 153, 7/7, enumerated 9 Jun 1880.

7.  George W. Wagenseller.  1904.  Tombstone Inscriptions of Snyder County, Penna.  Wagenseller Publ., Middleburgh, PA (facsimile hard copies available from HigginsonBooks.com; online at the Snyder County PAGenWeb site):

p. 177	ST. JOHN'S CEMETERY. Located at Fremont. List of deaths taken from Sexton's Record...
p. 181	Haas, John d July 23, 1881, aged 67 y 2 m 18 d.

8.  Birthdate calculated using Ben Buckner's JavaScript Birthday Calculator.

Name	Deathdate	Age at Death	Result
John	23 Jul 1881	18d 2m 67y	5 May 1814
(Calculated birthdates should always be prefaced with "ca." — you can't be certain the person who calculated their age did it correctly.)