Try this...

declare @date datetime

set @date = round(cast(getdate() as float),0,1)

SELECT

A.a_id,

C.c_id,

B.b_id,

D.d_id,

E.e_id,

F.g_id

FROM table_G G

INNER JOIN

table_A A

ON A.a_id = G.a_id and a.Created < @date

INNER JOIN

table_C C

ON C.c_id = G.c_id

LEFT JOIN

table_B B

ON B.a_id = A.a_id

LEFT JOIN

table_D D

ON D.b_id = B.b_id AND D.c_id = G.c_id

LEFT JOIN

table_E E

ON E.e_id = COALESCE(D.e_id, C.e_id)

LEFT JOIN

table_F F

ON F.g_id = G.g_id

WHERE

F.g_id IS NULL

In general, it is better to put conditions (where possible) into inline views instead of the where clause. That way, the number of rows is determined before the potentially billions of other rows introduced by the joins are considered. Also, if you're computing a value, do it in a variable before you put it in a join - it's a kazillion times faster. Another good way would be

declare @date datetime

set @date = round(cast(getdate() as float),0,1)

SELECT

A.a_id,

C.c_id,

B.b_id,

D.d_id,

E.e_id,

F.g_id

FROM table_G G

INNER JOIN

(select * from table_A where created < @date) A

ON A.a_id = G.a_id

INNER JOIN

table_C C

ON C.c_id = G.c_id

LEFT JOIN

table_B B

ON B.a_id = A.a_id

LEFT JOIN

table_D D

ON D.b_id = B.b_id AND D.c_id = G.c_id

LEFT JOIN

table_E E

ON E.e_id = COALESCE(D.e_id, C.e_id)

LEFT JOIN

table_F F

ON F.g_id = G.g_id

WHERE

F.g_id IS NULL

if you don't like inline views.